It's an elusive, smelly substance, made from fossilised whale faeces and bones. Frequently mistaken for pebbles and pumice, the naturally occurring ingredient on New Zealand's shores is literally worth its weight in gold.
Valued at up to $40,000 a kg, ambergris might be the most valuable poop in the world.
Last year a Dunedin woman found a 100g lump, the size of a golf ball, on Aramoana Beach and put it towards the down payment on a house.
So how is it that sperm whale scat came to command such a price, and why is it so hard to come by?
The first question is easy to answer, ambergris has been used in perfumes for the best part of 1000 years. There are references of it from Ming Dynasty China circa 1340AD and a trade for the substance began in Arabian Gulf, on the spice route.
Poached eggs and ambergris was reportedly a favourite of Charles II of England - although its use in courtly cooking became less popular, after its true nature became known.
In the Middle Ages nobody was quite sure where ambergris came from. Some speculated it was a kind of resin from seaweed, others thought it was beeswax from hives washed away at sea. The Chinese said it was the vomit of a mythical creature, giving it the name "dragon's spittle". They might be closest to the money.
Ambergris is part of a sperm whale's digestive process. Due to the whales' diet of squid - the waxy substance forms around the sharp beaks, which cannot be digested.
It's a form of protection as hard objects pass through the gut. Yes, ambergris is nothing but waxy whale poo.
Squid beaks are often used to verify ambergris finds.
While unremarkable in appearance, ambergris is particularly potent when burned or dissolved in alcohol.
Chemist Gunther Ohloff once described the fragrance for the Perfume Society as being "humid, earthy, faecal, marine, algoid, tobacco-like, sandalwood-like, sweet, animal, musky and radiant".
While there have been attempts to produce the scent for the mass market, purists will insist that nothing comes close to the real thing. Today it is still used by perfumers and is the secret ingredient in Chanel number 5. A little goes a long way.
New Zealand: unlikely ambergris capital
As a natural product secreted by whales it appears on beaches.
It is found wherever there is a population of sperm whales.
It is particularly prevalent in the Pacific and South Seas, appearing anywhere from South Africa to New Zealand.
In New Zealand there is no permit required to collect whale bones or ambergris that have already separated naturally from an animal.
The marine gold is theirs to keep, as long as the finder "as soon as practicable" notifies DoC.
However, as DoC permissions adviser Bethan Parry says there isn't a lot of information on the deposits.
"We don't track ambergris specifically, but as per the Marine Mammals Protection Act [MMPA] 1978, all findings of whale parts naturally separated are supposed to be reported to DoC," she said.
This is a way of making sure that the ambergris was found naturally. Back in the whaling era, it was a valuable byproduct of the now illegal trade.
"The data is only used when someone wants to export the ambergris so that we can look back and see that it was collected under the guidance of the MMPA."
Over the past six years there have only been two significant finds of the valuable poo.
Anton van Helden, a marine science advise for DoC, says that it's likely that there is a lot more washed up than gets found.
"People do find ambergris on a semi-regular basis in New Zealand.
"As it floats it can be weathered at sea for some time and accumulate where currents deposit material on the coast. People do in fact make a subsistence living off collecting and selling the material in New Zealand. Some have even trained dogs to sniff it out."
The quality and smell of the putrid poo only improves with age and time at sea. However, it can also make it harder to recognise, says van Helden.
It's hard to dissuade an ambergris hunter that what they found on the beach is not, in fact, a $10,000 nugget.
More often than not - finds on the beach lead to disappointment, not vast wealth, he says.
Van Helden does have some clues on how to discern the substance.
"I have asked people 'does it smell pleasant?' and they swear black and blue that it does…" but when they bring it in it will carry the smell of dead sponge or rancid fat.
"Ambergris has a very particular smell, pleasant in a musky/chocolaty/tobacco kind of way."
He says that many of the common substances mistaken for ambergris can be sea sponges or rubber.
It's not uncommon to be presented with lumps of old dog turd.
Where might it be found in New Zealand?
"If you find one piece of ambergris in your lifetime you are pretty lucky," says professional ambergris dealer Wendy O'Shea.
She and her husband Terry have been in the business for over 40 years.
She does not normally advise the public, as there have been previous incidents of over-hype making the general public think they can get rich quick. It is thought that less than 5 per cent of sperm whales produce the substance.
"Ambergris can be found in the lower South Island but it is also located all over New Zealand, although North Island finds are predominantly on the west coast."
DoC says they are aware of a small number of professional ambergris collectors. However, they keep their best fossicking beaches a secret.
There are a small number of collectors who have had this as their business for many years and keep their locations secret.
Given that only sperm whales are thought to create ambergris and these only navigate deep channels of water around New Zealand, there can be an educated guess as to where could be rich hunting grounds.
DoC says that Kaikōura and Rakiura/Stewart Island, where sperm whales are present all year round, would be a good place to start. Though chances of a find are still very slim.
Advising on ambergris deposits can be a dangerous business.
English-born biologist Christopher Kemp reportedly received death threats and hate mail over his book on "floating gold".
Floating Gold: A Natural (and Unnatural) History of Ambergris which he wrote while living in Dunedin was thought to be the bible on finding valuable whale poo.
In an interview with the Otago Daily Times Kemp said he was threatened with legal action and angry letters for publishing Oreti Beach in Invercargill and Mason Bay on Stewart Island as top spots for the substance.
However, he said these locations were only of limited help. Kemp said it was not finding but identifying the super rare whale droppings which was the most difficult task.
"I tell people they've got to sniff a lot of dog droppings before they find a bit of ambergris," he wrote.