Along a ridge on the West Coast of the South Island, New Zealand had a choice between money and environment. It chose money.

THE DISCOVERY

As soon as it was finally found, a native creature was forgotten

When you think of New Zealand's native species, you may imagine comical looking birds wandering native bush on foot, or giant weta clinging to mossy branches. Perhaps you picture tiny frogs that can't croak or Kea soaring through the mountains.

One of our rarest native species has a much stranger habitat.

It lives in hundreds of plastic boxes, many of which are used ice-cream containers, tidily stacked in two cold stores in Hokitika between the river and the public swimming pool.

A more precise description: The species' known habitat spans a few long strides, maybe 15m, at the southern end of Sewell St behind the dilapidated heritage building dedicated to King Dick Seddon and the brick furnace identified as 'Jim's Inferno'.

The species is Powelliphanta augusta, named for its original habitat, a cloudy mountaintop above the sea.

The species is ancient but its paper trail is young. The article detailing the species' existence, published in 2008, is highly unusual for a species that still existed: It described its known habitat entirely in the past tense. It had lived on the highest peaks of the ridgeline; its preferred habitat was the moist soil under the patchwork of tiny plants above the treeline.

By the time the species was formally described, its habitat had already been replaced. It was no longer the mountain but two cold stores behind the local Department of Conservation (DOC) office, in a pseudo-car park separating the main building from an annex, where the keepers are based.

Three DOC rangers are assigned to the captive programme, as it's officially known. They carefully note what the captives eat, how much they weigh each month, and how they breed. Their handwritten observations are stored in thick binders amassed on a desk, chronicling years of work; a snail soft toy rests on top.

Perhaps some of the snails have an innate sense this is not their home. It's not the mountain ridge where rain fell in sheets, as if tipped from a bucket; where the ground froze over in the winter and titanic gales hissed over the Tasman, rattling the tiny trees and shrubs that to us would have looked like a bonsai forest but would have been mighty Totaras to the tiny fauna that had lived there.

It took the species millions of years to adjust to that brutal environment, which it had slowly conquered while the mountain emerged from the clash of tectonic plates, but just a few months to undo it with big metal machines tearing into rock.

There are 1400 snails in the fridges, which is nearing capacity. Around 300 of them once lived on the mountain, until they were taken by workers crawling on their hands and knees, digging through soil, more than a decade ago.

Some of the snails are nearing 30 years old and have grown so large they would fill the palm of a child's hand. They've had babies and their babies have had babies. It is a blooming family tree whose branches are pruned by the physical confines of lives in separate containers, across two fridges, a few strides apart on Sewell St.

These snails are at the center of one of the strangest conservation stories in New Zealand. To some conservationists, it is also one of the most damning, and still provokes anger more than a decade later.

When the snails were moved from the mountain over a few chaotic months, ferried across the South Island in chilly bins with nowhere to go, it was unclear if it would all end with the species' extinction, but they were moved anyway.

New Zealand had a choice between money and environment and it chose money.

More than a decade later, the experiment is ongoing, with the outcome no clearer then when it started. The snails have been in captivity longer than most expected, in a kind of purgatory, because there is still no verifiably safe habitat for them in the outside world.

Without the fridges and the DOC staff caring for them, the snails would be extinct. But their miraculous survival is a constant reminder of the fact they were put there in the first place.

The botanists from Nelson were roaming the Stockton plateau one day in 1996 when they stumbled across something odd.

They were six large shells, each with a handsome walnut coat, swirled in a koru-like pattern. They were evidence of snails, high in the mountain.

There's a reason why you normally find snails in a garden. Most snails thrive on damp soil and temperate weather, with lots of vegetation to eat.

The Stockton plateau offers the exact opposite. It is a kilometre above sea-level, in the clouds, with little sun and high winds. Its annual rainfall of more than 6m makes it one of the wettest places in the country and the sparse topsoil is intensely acidic, likely corrosive to their shells.

Because it was such a strange place to live, it became a massive evolutionary advantage.

Up in the clouds, there were few weka to claw through their brittle shells or possums to crack them open like walnuts, no pigs to tear them to shreds, which have all devastated their cousins in the forests. The hard work of conquering the mountain had been a protective blanket against the ecological chaos down below.

When the botanists returned to Nelson, carrying the shells in a bag, they took them to the local DOC office.

They were given to Kath Walker, DOC's snail expert, who knows more about native snails than most. At the time, only one snail species was known to live in such a hostile location: Powelliphanta patrickensis, one of New Zealand's giant, carnivorous Powelliphanta species.

Walker didn't think much of it. Based on the described location and a cursory scan of the shells' appearance, she reasonably assumed they were P. patrickensis.

If Walker had reason to examine the shells closely, she would have noticed the subtle differences in the shell pattern, which only an expert's eye could pick up; the narrow red spiral lines, the slightly less glossy shells. A new species.

Even to an expert, the shells look remarkably similar to P. patrickensis.

The first sign of an ancient species was stored and promptly forgotten. 

CAVIAR BEFORE CLIMATE CHANGE

When Stockton promised a premium, Solid Energy started selling

A coal seam at Stockton mine.

A coal seam at Stockton mine.

The state-owned miner CoalCorp was having image problems.

The company was formed in 1987 out of the husk of the indebted government department State Coal Mines.

The newly state-owned enterprise undertook a ruthless restructuring: It shut down its unprofitable mines, sacking more than one thousand miners, and looked for ways to aggressively expand in areas likely to be profitable. One of its first moves was to obtain a licence to mine the Stockton plateau.

A new environmental ethic was emerging around the same time, particularly around what was increasingly seen as a major threat: climate change.

CoalCorp was worried. It had sponsored Fred Singer - a physics professor who had been well-known for spreading the false notion that secondhand tobacco smoke wasn't bad for one's health before becoming a leading climate change denier - to speak to industry figures in New Zealand. In its annual reports, the company portrayed climate change as an ongoing and uncertain debate, in which proactive regulation would be catastrophic for the economy.

On the more public front, however, it wanted to change its image. CoalCorp as a brand was severe, unfriendly, so it opted for something lighter, signalling a new direction as an energy supplier: Solid Energy. Its logo, a lump of coal, became a rising sun.

Stockton mine was growing rapidly and would soon become the country's largest open-cast mine, a massive pit hollowing the mountaintops that would fuel the engine of the West Coast economy. 

At first, the mine extracted half a million tonnes of coal per year. That amount doubled, then doubled again. The mine's footprint grew so quickly it swallowed the plateau, swelling like a balloon. 

Few things are as destructive to the environment as open-cast mining and Stockton was no exception.

The sub-alpine landscapes on the plateau were stripped bare and mountaintops were chopped. The coal seam was 30-40m beneath the soil, covered by a thick layer of sandstone, which was blasted away with explosives that fired dirt and rock into the air.

Despite being a state-owned enterprise - bestowing it with at least a small sense of public accountability - Solid Energy had dubious environmental practices, which it later acknowledged.

Locals living downstream of Stockton were keenly aware. The mine sits above the Ngakawau river, which drops steeply down the mountain, over waterfalls and down narrow valleys, through Ngakawau township and out to sea. By the early-2000s, the river would become so polluted with coal fines it ran black; poor acid drainage made the river poisonous and stained the thick, native bush yellow.

The company later cleaned up its practices at great expense. But in the mid-2000s, Solid Energy was battling the perception it had little regard for the environment.

Solid Energy was fighting another battle: it was starting to use up its most valuable coal.

The mine was pushing deeper into its licenced area, up against the borders it shared with the conservation estate.

Solid Energy's analysis showed one stretch of its western border contained a jackpot. The seam was above a coal stash potentially worth hundreds of millions of dollars, a premium product Solid Energy executives would describe as "the caviar of coal".

Most of the coal in New Zealand is low-quality. But some areas have premium coal, which is blended with the lower quality product to increase the value of the entire supply.

Without the small pockets of good coal, the rest of it would be worthless.

It was 2004. Coal prices were high, and there were fears swift action on climate change would cause them to plummet.

Solid Energy started selling its caviar before it even started digging. It would be months before the ridge could be blown apart and coal put on the swinging boxes to sail down the aerial ropeway and into the sorting facility that towers above Ngakawau, where it's loaded onto the cross-country train that tunnels beneath the Southern Alps on its way to Lyttelton Harbour.

Then everything stopped.

MOVING OUT

The permanently temporary home for one of our rarest native species

DOC ranger Rodney Phillips with the Powelliphanta augusta population. GEORGE HEARD/STUFF

DOC ranger Rodney Phillips with the Powelliphanta augusta population. GEORGE HEARD/STUFF

Rodney Phillips approaches the drab trailer, which is quietly humming like an air conditioning unit, and swings open the doors, unleashing a quick blast of cold air.

The trailer is stuffed with plastic containers, neatly stacked from ground to ceiling, apartment style.

The sorting system is simple. The white ice-cream containers house the oldest snails, sort of like a retirement unit. The larger Sistema plastic containers - the same ones you'd buy at the supermarket - each have three second generation snails that have reached adulthood.

The smallest containers have the littlest snails. It takes around eight years for them to reach full size, and there are so many they take up most of a fridge to themselves.

The snails don't have names but they do have codes, which indicate which section of the mine the snail came from.

There were dozens of mining blocks across the ridgeline, each ranging from 1400m2 to about twice that. After they were picked up, the snails were kept in those blocks to maintain genetic diversity; future generations will stay in those groups, too, forever united in clans defined by the geography of the mine that swallowed them.

The snails are well cared for.

Their containers appear small from the outside, but given their propensity to sit still, must to the snails be a vast landscape with corners they may never uncover.

A container is opened and light streams into the box, inspiring one snail to start moving. It stretches out of its shell, slowly, as if the air was thick like molasses, before toppling off its tiny mountain of moss and beech litter and soil.

Its code is 10C/134, meaning its mother was collected from mine area 10, block C.

"In here they've got a pretty easy life," Phillips says.

"They have a constant temperature, constant light cycle, constant food. It's a pretty stable environment for them."

Before the P. augusta were put into fridges, there had been no large scale captive programme for Powelliphanta. They were a deeply mysterious genus, doing who-knows-what in the remote bush of the South Island's western flank.

Powelliphanta, we now know, behave more like mammals than typical invertebrates. They only eat meat and live long, nocturnal lives, seemingly sharing more in common with Kiwi than their snail relatives overseas.

Because of the captive programme, one of our most recently discovered snail species is also the one we know the most about.

P. augusta are hermaphrodites which both lay and fertilise eggs. Their eggs are tiny, pink orbs, a bit like delicate bird eggs, which take on average 200 days to hatch but sometimes much longer, as long as 1000 days.

We know that sharp changes in light can induce the snails to breed and they don't need more calcium, even when it's available; they die at high densities but never meet at low densities.

Curiously, they still lay their eggs in spring, even though conditions in the fridges are the same year round. Even the snails that have never known a world with seasons are ruled by them.

Of all the facts learned about the snails, perhaps the most interesting is how they eat.

Despite a famously slow gait, New Zealand's native snails strike their prey like snakes, snapping onto a worm and sucking it up like spaghetti. A video of a captive P. augusta eating a worm has nearly 2 million views on Youtube, about as viral as any obscure snail could hope to go.

While the fridges are comfortable, the current set-up isn't what it once was.

As part of the deal that put the snails in the fridges, Solid Energy had to pay for their upkeep, which cost the company at least $200,000 per year. Over the course of the decade, the company spent an estimated $7m on the programme.

The snails weren't expected to stay in the fridges longer than a decade, so that was the period agreed to.

For a while, the snails lived in climate-controlled environmental chambers, specially built by a company in Lower Hutt, which could regulate light and temperature and even simulate rain; Some of the snails were on stainless steel trays, not ice cream containers.

But when the 10-year mark came around, there was still nowhere for the snails to go.

It had also become clear that Solid Energy, the snails' benefactor, was in profound financial strife. No longer on the hook for the snails' upkeep, it started selling its assets.

The environmental chambers were dragged out of the DOC office, loaded onto trucks and driven to Christchurch, where they were sold at auction.

It fell to the cash-strapped DOC to keep the programme running. Today's set-up is humble, but comfortable. The cooling stores are owned by DOC; the containers are cheap and the worms are grown in compost bins fed with vegetable scraps from DOC staff.

The ice-cream containers are easy to laugh at, but they're invaluable. They're light, stackable, keep the humidity right, and most importantly, they're free (minus the cost of the ice cream). New Zealand conservation is littered with stories of DIY ingenuity, and the snails are no different.

"If we only had a few hundred here we probably could keep them in boutique environmental chambers," Phillips says, "but because it was on that scale, we settled on something we knew would work."

It costs around $51,000 per year to keep the programme going, which is paid for by taxpayers.

Conservationists say it is a small price to pay given the alternative is extinction.

THE UNHAPPY VALLEY

Three years of continuous protest

Santa joins a protest against the Happy Valley mine, outside the Solid Energy building. JOHN KIRK-ANDERSON/STUFF

Santa joins a protest against the Happy Valley mine, outside the Solid Energy building. JOHN KIRK-ANDERSON/STUFF

There's a drenched rainforest at the eastern border of Stockton Mine, bleak and grey and blanketed in fog, that locals like to call Happy Valley.

Happy Valley had always been untouched, even by the neighbouring mines, which made it an oasis of biodiversity. The valley was clad with red tussocks and beech forest, carved with clear streams and native animals like kiwi. Getting there required a half-day hike through thick, wet bush, likely in punishing rain and through tranches of mud.

Solid Energy had noticed something else in the valley - approximately $850m worth of coal.

In 1998, part of the valley had been recommended for protection by DOC, which deemed its biodiversity values to be nationally significant. It was largely due to a rare red tussock wetland, as well as a Great Spotted Kiwi population.

The recommendation carried no legal weight, however, and the company was given approval to mine the valley in 2005, despite intense opposition from environmental groups.

Where the original P. augusta habitat was located in relation to the mine, and what remains now.

Solid Energy's promises to preserve the environment as much as possible were met with scepticism.

One technique seemed particularly ludicrous. It would dig up the rare tussock wetland, store it off-site, and roll it back onto the land like a carpet once the mining was done. It was a technique that botanist Sir Alan Mark, at the time, noted had never been successfully attempted anywhere in the world.

Many scientists were called to give advice during hearings to decide on the application. Among them was Kath Walker, DOC's snail expert.

Along with the Great Spotted Kiwi, the valley had a population of another rare native species: P. patrickensis, the hardy snail known to live on the plateau.

While preparing her evidence, Walker pulled out the P. patrickensis shells stored in the Nelson DOC office.

On close inspection, she noticed some of the shells were unusual. The colours were similar, as were the vertical swirls, but some had thin, reddish bands she couldn't recognise.

Walker quickly realised they weren't P. patrickensis but something else entirely.

She rushed to track down the botanists who had found the shells nearly a decade earlier, who gave her a precise location of where they had been found, an escarpment near Mount Augustus.

When she arrived there in early 2005, she found a large hole in the ground. The only known habitat of this new species had been destroyed.

There was one stroke of luck. The long escarpment effectively marked the border separating the mine and conservation land.

Due to the way the border was drawn on the mine licence, a small peak that was part of the ridgeline was technically within conservation land.

That peak is today known as the DOC triangle, a weathered little island in what was once a vast ocean, and the last remaining natural habitat for the species: "It's our great white hope," Walker says.

After Walker saw the mine had taken over the new species' habitat, she found a population on conservation land. She correctly inferred there were more within the mine site, on areas yet to be dug up.

It was a last minute reprieve for the species. It's impossible to know how widely spread they originally were, but it was likely at least 20 times what remained when Walker arrived.

"They were probably extensive over that north-eastern end of Stockton plateau," she says.

"It was down to maybe five per cent, two per cent. Not much was left."

After some analysis, it was estimated the remaining snail habitat was around 5ha, nearly all of it within the mine, in an area that would shortly be dug up.

It was a metaphorical crossroads. The economy and the environment, two trains on the same track, were about to collide. 

In the battle that ensued, Solid Energy was Goliath.

Its David was a scrappy group of environmentalists calling themselves the Save Happy Valley Coalition, which had formed to oppose Solid Energy's intent to dig up Happy Valley.

The group's main opposition to the mine was on climate grounds. Digging up the coal at Happy Valley would add millions of tonnes of carbon dioxide to the atmosphere, which members of the group saw as irresponsible, particularly from a state-owned enterprise.

The group quickly latched on to conservation issues, too. Happy Valley had a Great Spotted Kiwi population, which was an invaluable selling point for the group's aims, given Solid Energy could not rule out that at least a few birds would die.

Its protest actions started small but grew quickly. Some members tied themselves to a train-track to stop a shipment of coal to Lyttelton. Others dug up the lawn at Solid Energy's Christchurch headquarters.

At the mine company's annual conference, protesters dressed as Santa Claus invaded the stage with bags of coal. One of them threw a pie at chief executive Don Elder, which narrowly missed.

The series of small aggravations culminated in one of the largest collective actions the environmental movement in New Zealand had witnessed for decades. Some protesters set up camp in the valley, informally occupying it for three years.

"We were much more agile than a big state-owned enterprise with all their lines of command," recalls Frances Mountier, who was a member of the coalition.

"We were a grassroots group up against a big state-owned enterprise, with all of their budget.

"They definitely used it to litigate against us."

Solid Energy's response to the increasingly irritating group was severe.

When Save Happy Valley released a satirical environment report purporting to be from Solid Energy, the company unsuccessfully sued it for defamation.

It then, notoriously, hired private security firm Thompson & Clarke, which paid a student to infiltrate the group and report on its activities, causing a scandal when it was revealed by journalist Nicky Hager. The use of Thompson & Clarke later extended to Government departments, which is now the subject of an inquiry.

The mine at Happy Valley was delayed for several years, but ultimately proceeded in 2009.

Today, much of the area is known as the Cypress Mine.

This was all unfolding around the time P. augusta was discovered at the other end of the mine. Solid Energy was in the bizarre position of fighting two environmental battles, both involving snails, simultaneously.

The two issues became one. Save Happy Valley joined the fight to save P. augusta, alongside other environmental groups such as Forest & Bird, which was also fighting the Happy Valley expansion.

The problem was that the mine was moving quickly.

Solid Energy had already sold some of the coal beneath the snails, and it believed it wasn't required to take any action regarding the species. An opinion from Crown Law agreed.

It was primarily due to an odd legal loophole. Most mines in New Zealand were licenced under the Coal Mines Act, which predates the Resource Management Act, meaning the mines are mostly subject to environmental rules under the former, not the latter.

Solid Energy had offered to relocate 100 snails, but argued it didn't even have to do that, and would go ahead with its mining.

Forest & Bird took the matter to the High Court, arguing the miners were still subject to the Wildlife Act, which makes killing a protected species illegal. It was the only argument the group had.

"We looked at every legal mechanism we could to protect them," says Debs Martin, a Forest & Bird field officer who was involved with the action.

"We couldn't even argue the cost of climate change in the Environment Court. When you're arguing things under legislation, the legislation can be quite restrictive for what the actual full effects [of the activity] are."

The advice from DOC, via Kath Walker, was to leave the snails alone, a view supported by other expert witnesses.

The court's judgement was withering. Solid Energy's decision to mine the snails was "noxious," it said, and the court thought "there is little doubt that from the scientific and environmental point of view, the snails should not be moved".

Under the law, however, it could proceed - as long as it got a wildlife permit from then Conservation Minister, Labour MP Chris Carter, to move as many snails as it could find.

It took about six months for the approval to arrive. In a statement at the time, Carter said because the licence had been granted under the Coal Mines Act, he was forced to consider economic factors.

"This decision has been an exceptionally difficult one to make because the issues involved are finely balanced," he said.

In the months afterwards, workers crawled along the plateau on their hands and knees, picking the ground apart in search of snails.

They had expected to find around 250, certainly no more than 1000. When the process came to an end, more than 6000 snails had been discovered, along with around 8000 eggs.

It was both good and bad news. That there were many more snails than expected was promising for the population, but did not change their threat status, because they all lived in a tiny area, which was about to be destroyed.

Some of the snails were relocated elsewhere on the plateau, unknown if they would survive. The rest needed somewhere to live. 

The company had bought around eight domestic fridges like you'd find in most New Zealand homes, but far more were needed to house that many snails.

The first group was moved in chilly bins to Nelson. When it was clear there would be too many to keep there, they were hurriedly shifted to Hokitika, where they were held in cold stores until the environmental chambers were ready. 

Thousands of snails needed to be fed, and there weren't enough worms to feed them. The hunt for worms was so desperate DOC staff sifted through cow pats on dairy farms. 

It all happened in a breathless flurry. The last survivors of an ancient species frantically shuffled between chilly bins and fridges, public servants digging through poo while the miners' diggers lined up and took to the jagged ridge at Mount August like lumberjacks to a tree.

"The terrible haste with which this happened should never have eventuated," Debs Martin says. 

"We never accepted them going into fridges at all, because that's not what you do with threatened species. You protect their habitat where they are.

"For those that were desperately doing what they could, and caring about it, it was a really difficult time. It was quite emotional for some people who were trying to protect wildlife who were just like 'what's going on here'?"

THE MAGIC CARPET

A plan to peel the ground away, remove it for a while, then return it

Restored habitat when Rod Morris visited the plateau in 2010. ROD MORRIS/SUPPLIED

Restored habitat when Rod Morris visited the plateau in 2010. ROD MORRIS/SUPPLIED

The snails were long gone when Rod Morris became suspicious.

The filmmaker and wildlife photographer had heard a stream of good news about Stockton and the work being done to protect the environment.

Solid Energy had been hyping up its use of an experimental technique called vegetation direct transfer (VDT). It was what it had proposed to do with the wetland in Happy Valley. It would peel off the original vegetation like skin, stash it off-site, and put it back when the mining was done.

The idea that you could roll native plants onto a mountain like artificial turf on a suburban lawn seemed absurd, but Morris was willing to be convinced. He asked to visit the plateau so he could write a story for the Forest & Bird magazine.

Solid Energy agreed, so Morris went along to the corner of Stockton that had once been the home of P. augusta, the last remaining stump on the ridgeline.

He had seen photos of mines, but never stood before one and felt the immensity of it. He likened it to seeing a photograph of an elephant charging at a photographer; mildly interesting to the viewer but profoundly emotional for the photographer about to be stomped on.

"Looking into that great yawning chasm of total and utter destruction had that effect on me and I thought: 'My God, I didn't realise this is really going on in New Zealand'," Morris recalls.

"Not only had they removed the mountaintop on which the snail existed, they were destroying this landscape."

He studied the newly replaced habitat which was to become the new home for the snails when they left the fridges.

To an untrained eye, it would look fine, he says. But his familiarity with that environment meant he knew exactly what he was looking at.

"I was looking at all the wonderfully diverse plants… which were all dying on this supposedly magic carpet of recovery," he says.

"Looking at it I thought it was a total and unmitigated disaster. I found it all pretty distressing."

He wrote as much in his article, which he says resulted in Solid Energy banning him from the plateau.

"It made me realise just how skewed and biased the PR machine over there had been," Morris says.

The saga had largely been portrayed in a light sympathetic to Solid Energy, aided by an at times credulous news media. A 2010 thesis examining media coverage of the issues found newspaper reports (including those by publications owned by Stuff) were far more likely to quote Solid Energy than either experts or those opposed to the snails’ relocation.

Several stories, for example, repeated Solid Energy's claim it would cost $8000 to move each snail, which proved to be inaccurate. One headline simply read: ‘Snails threaten Stockton mine jobs’.

The imminent decline of the coal industry floated above the whole drama like a rain cloud. The idea that desperately needed work for miners would be derailed by snails sat uncomfortably with a region grappling with a post-mining future.

It got to a point where environmental activist Peter Lusk, then with Forest & Bird, said his mailbox had been blown up with a pipe bomb, which caused him to retreat from his activism on the issue.

After the snails were moved, there was little attention on how the species was faring in the fridges, but plenty on Solid Energy's balance sheet.

In its annual report, Solid Energy said moving the snails had cost it $10m, with a further loss of $25m from the coal it had sold before digging it up.

Despite publicly hailing its cooperation in moving the snails, one of the company's annual reports questioned whether "there could have been better uses" for those costs.

It all culminated with a Solid Energy-produced 20-minute documentary called Snail: The Movie, which chronicled the effort to relocate the snails.

It largely comprises an interview with Solid Energy's then environment adviser Mark Pizey, detailing the care that went into moving the snails. (Pizey did not return a request for comment for this story).

The production reportedly cost the company $50,000, and was distributed to all shareholders.

It made no mention of the court order, or the protest action. It did not mention how Solid Energy argued for the right to mine through the snail habitat. After it's release, chief executive Don Elder pre-empted the inevitable criticism, saying: "We never intended this to be a propaganda movie, although I'm sure some will see it that way".

That was correct.

"I still can't bring myself to watch it," said one person involved in the snails' protection.

A few years on, the magic carpet at the mine has continued to grow.

Whether the VDT area will ever be an appropriate long-term home for the snails is an open question, given the differences to the original habitat.

The last piece of original habitat, the DOC triangle, was once the lowest point on the ridgeline, but is now the highest. Chopping around 30m from the mountaintop has meant less cloud cover, which could mean less moisture, which is vital for snails to survive.

The VDT area has small chasms, creating little islands; weedy native plant species have prospered. It may be a good enough habitat at some stage, but experts say it likely isn't right now.

It leaves the DOC triangle, the small nub of conservation land, as the most promising base for the species.

"The last little fragment that was on conservation land is still there, but it’s precarious because it’s close to the mine," Kath Walker says.

"Taking the top off the mountain means it’s not catching as much cloud, so we don’t really know if that little sliver of habitat that’s left is going to maintain the snails forever."

It's called a triangle because it has been carved by the mine on three sides. The miners were ruthlessly precise in using the area they were allocated, which included digging into the sides of the ridge that happened to be in the DOC estate. The remaining stump bares a passing resemblance to the famous cow island created by the Kaikōura earthquake.

The triangle's steep slopes are eroding, sending rocks tumbling into the mine and further whittling away at the snail habitat. It's likely too small to sustain an entire species.

DOC has been experimenting with introducing the snails elsewhere. They've moved some to Mt Rochfort, at the southern end of the plateau, but it's home to P. patrickensis, and it's unclear if the two species can co-exist.

They're also trying an area below the original ridge-line, but it's much lower down. Even subtle climate differences can be devastating for a species that spent millions of years adapting to a particular place.

The biggest risk, strangely enough, is drought. On a day-to-day basis, the snails can probably survive with less moisture then they adapted to, but what happens when a drought is added on top of that? It could kill the entire species within a few months.

That's why the captive population is so significant. It is still unclear if the snails being re-released into the wild are being sent to their deaths.

"This captive population is an insurance against those ones," Walker says.

A series of images released under the Official Information Act show issues at the mine left by Solid Energy. Part of the best habitat is eroding into the mine.

A series of images released under the Official Information Act show issues at the mine left by Solid Energy. Part of the best habitat is eroding into the mine.

A new habitat area is beneath a fence, intended to protect it from rockfall. In 2016, the fence was dilapidated.

A new habitat area is beneath a fence, intended to protect it from rockfall. In 2016, the fence was dilapidated.

Part of the re-vegetated area shows plants dying.

Part of the re-vegetated area shows plants dying.

A STRANDED ASSET

After the money’s gone, what becomes of what is displaced?

One of the original southern P. augusta. GEORGE HEARD/STUFF

One of the original southern P. augusta. GEORGE HEARD/STUFF

In the hundreds of containers lining the fridges, a few have special significance.

One of the many incredible things about New Zealand's native snails is how different they can look, even if they're geographically close.

Within a few kilometres, you can find different species and sub-species which never overlap, each on their own private evolutionary trajectory.

Snails have told us what the world used to look like. The similarity between snails found in both Nelson and Horowhenua, for example, was early evidence of an ancient land bridge between the two areas.

"It always seems to me like they're painted on the landscape," Kath Walker says.

"You can tell where a snail is from by the way it looks. The shells show genetic differences. We've got this patchwork that if we can put it together, like a jigsaw, we can work out what New Zealand was like five, 10 million years ago."

One of the most striking discoveries about P. augusta since its captivity is that there are three different types, separated long ago.

Nearly all of the more than 6000 snails collected were from the northern end, which had yet to be mined. But 24 of the snails were collected from the south, which had already been destroyed. They are likely distinct enough to qualify as a sub-species. A few more were in the middle, a sort of hybrid between south and north.

The northern and southern types lived a few hundred metres apart but rarely seemed to crossover; They were likely separated by a single forested gully, or a sudden event like a fire long ago. For thousands of years they would have evolved as neighbours. The southern types are bit bigger, and usually a lighter colour. Side by side, they could be a different species entirely.

Five of the original 24 southern snails are still alive, each well into their 20s. They have successfully reproduced, and now there are around 150 southern P. augusta, most of them babies.

There are roughly the same number of southern P. augusta as there are Kākāpō. When Kākāpō numbers dropped to 50, they had an international advisory group and round the clock minders, hot water bottles in their nests and vets on call. The southern P. augusta are well cared for, too, but remain obscure. As it would be with Kākāpō, releasing them all into the wild at once would be an enormous risk.

DOC was unsure how it would look after the species when it was tasked with starting the captive programme. There was no local precedent.

It has come with occasional bouts of trouble. In 2011, one of the fridges malfunctioned, killing around 800 snails.

It happened due to a series of improbable events - the chiller unit automatically reduced the temperature in response to the malfunctioning temperature gauge, which was recording incorrect warmth. Because it was a long weekend, it was discovered too late.

It was a devastating blow for the DOC staff who had spent years experimenting to make the conditions just right. (The chiller unit is now connected to a text message warning system, and snail numbers have fully recovered).

While DOC has figured out what works, how long the programme should last has been a dilemma for the department, which is obliged to save a species with no viable habitat. The species' recovery plan stresses persistence is the aim - its goal, first and foremost, is to keep the species alive.

Internal debate about the species' future has been fraught, documents obtained under the Official Information Act show, and almost resulted in the programme being axed entirely.

The documents show a proposal to release all of the captive snails into the wild by the end of 2018, "mothballing" the facility in case they needed to be brought back.

That didn't happen after expert advice warned it would be risky, particularly for the southern type.

“Early release of all snails would almost certainly mean extinction/swamping of the southern subspecies and loss of genetic diversity within the species,” part of the advice said.

"Extinction of the southern sub-species would be likely and a reduction in genetic diversity probable."

It was just one of many issues. The tiny area of suitable habitat put the species at risk of "stochastic" events (basically a random disaster, like a fire or a drought); an early release "could pose high reputational risk for the Department".

The species was named a priority on the draft threatened species strategy - chosen by an algorithm used to decide which species were most worth saving - which would have meant the species' population would need to increase, not just persist.

So what next? The captive programme is safe until 2020, funded by the taxpayer. DOC is exploring ways to cut costs - they could include scaling the programme back, a privately run model, or corporate sponsorship.

What happens after 2020 is still unclear, and depends on a lot of unknowns. By then, it would have been 10 years since they started monitoring the re-released snails in the wild, and nearly 15 years since the species was refrigerated.

In that time, Solid Energy dug up the coal but accumulated $400m of debt from which it couldn't recover. It went into liquidation in March.

Over the life of its wildlife permit, Solid Energy paid around $7m to keep the snails alive in fridges, as well as the original $10m cost to move them.

When the company hit trouble, the Government took on the company's environmental liabilities at a cost of more than $100m, many times the price of keeping the snails alive. The taxpayer continues to subsidise Solid Energy by paying for the snails it was willing to sacrifice. The term for the things an industry abandons before they're used up is a 'stranded asset'. Usually it's a power plant, or a mine. In this case, it's a native species.

Some of the conservationists involved in this saga see it as a horror story; undoubtedly a metaphor for something grim, or a microcosm for the wider forces that govern New Zealand and its environment.

"The New Zealand public and the Department of Conservation are always left holding the baby," Rod Morris says.

"They're left tidying up the mess [after] these flash-Harrys promise wonderful employment. It's just the nature of boom and bust industries, we just somehow don't seem to learn from one experience to the next.

"If ever there had been a case to leave the mountain alone, leave the snails where they were, Mount Augustus was that case. And we mucked it up."

For those who fought against the snails being refrigerated in the first place, the current dilemma is a painful realisation of their worst fears.

"This is exactly what we predicted," says Frances Mountier, of Save Happy Valley.

"A whole species is languishing, it has nowhere to go … by pushing through with the mining of Augustus, Solid Energy effectively locked them into this fate."

The name Augustus means to inspire, to be dignified.

In her description of the species, written after the peak was gone, Walker said the name was a fitting memorial to what had been lost, which would live forever in the name of the species that evolved alongside the mountain.

In a parallel universe, Mount Augustus still exists, and the snails live happily in their odd little habitat. Walker looked carefully at the bag and noticed the subtle differences only she could have spotted. There was more habitat remaining, with more snails, and a population could have been saved.

P. augusta are not snails but stunning birds that soar, not slither, a species New Zealanders proudly claim as their own. Instead, they are snails, entering their second decade in a fridge.

Clarification: This story was updated to clarify that Fred Singer was noted for downplaying the health risks of passive smoking, rather than smoking more generally.

Words & layout: Charlie Mitchell

Visuals: George Heard

Cover image: Stacy Squires

Design: Aaron Wood

Editor: John Hartevelt