Next time you go for a leisurely stroll along the beach, keep your eye out for a strange smelling rock. It could be ambergris.

A British couple were surprised to find a large rock as they walked along a beach, and even more surprised to hear that it was in fact incredibly valuable. Some people are calling the weird rock “whale vomit,” but it could be ambergris worth $70,000, writes Gabrielle Sorto for CNN.

Possible Ambergris Find Could Be Worth $70,000

Strange substance produced by tiny percentage of sperm whales

“Ambergris is definitely not vomit,” Christopher Kemp, author of “Floating Gold: A Natural (and Unnatural) History of Ambergris,” told CNN. “It’s more like poop, and it comes from the same place as poop, but it’s only made by a small percentage of sperm whales, as a result of indigestion.”

“Ambergris feels a little waxy, and smells very complex: a mixture of dung and the ocean, and old wood, and tobacco, and moist earth, and ozone,” Kemp said.

In fact the strange substance is used to make the smell of perfumes last longer on the skin. Gary and Angela Williams were struck by a strong smell as they walked on Middleton Sands beach near Morecambe Bay in the United Kingdom, and followed their noses until they found a big lump of what they now think is ambergris.

Ambergris could make couple some serious money

“It was down a section of the beach where no one really walks,” said Gary, who is an engineer.

“It smells too bad, though. It’s a very distinctive smell, like a cross between squid and farmyard manure. It feels like a rock hard rubber ball. Its texture is like wax, like a candle. When you touch it you get wax sticking to your fingers. If it is worth a lot of money, it will go a long way towards buying us a static caravan. It would be a dream come true,” he said.

Some people call the substance “floating gold” and it is only produced by a very small percentage of sperm whales. Sometimes it floats around in the sea for decades before washing up on the shore to be found by lucky people like the Williamses.

Hard to know if find is real

Don’t get too excited about this latest get rich quick scheme though. Ambergris is incredibly rare and is only found on very few occasions, and you could waste years trawling beaches in the hope of finding it.

Many people believe they have found ambergris and later find out that they haven’t, according to Kemp. “That’s why so many people think they’ve found it, and then discover they haven’t,” he said.

Kemp says that the Williamses find might not be real ambergris. He says that the substance they found is “a little too waxy” and could in fact be animal fat rather than ambergris.

However if the find is the real deal it could net the British couple some $70,000. They are apparently in talks with interested parties in New Zealand and France about buying the lump.

One lucky 8 year old schoolboy found a 1.3-pound lump of ambergris in 2012. That particular find was worth around $63,000. Kemp says that high-quality ambergris is worth thousands of dollars per pound.

The whales are not harmed when ambergris is harvested, however trading in the substance is banned in the United States. Lawmakers imposed the ban in an effort to avoid the exploitation of the endangered whales.