Taking a long walk on the beach anytime soon? Sniff around for a smelly rock, because if you do find one you could get really lucky.
Recently, a couple in the UK stumbled across a large rock that many are calling "whale vomit." Gary and Angela Williams were following a pungent smell while walking on Middleton Sands beach near Morecambe Bay when they stumbled across what they believe to be a large lump of ambergris -- a rare substance used to make perfumes last longer on the skin.
Australia slams Japan Antarctic whale hunt
If what the British couple found is genuine ambergis, it could fetch them an estimated $70,000. The couple is reportedly in negotiation with potential buyers in New Zealand and France.
"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.
The substance, which is often called "floating gold," is produced only by a small percentage of sperm whales. It can float in the ocean for decades and in time washes up on shore.
However, ambergis is extremely rare and found infrequently and it's very hard to know if you've actually found ambergris, Kemp said.
Antarctic blue whales belong to three populations: study
"That's why so many people think they've found it, and then discover they haven't," he added. Kemp suspects that the couple's find may not be genuine ambergris because the substance is "a little too waxy" and looks more like animal fat than ambergris. Good, high-quality ambergris is worth thousands of dollars per pound according to Kemp.
In 2012, an 8-year-old British schoolboy found a 1.3-pound mass of Ambergis in sand that was worth about $63,000.
This article originally appeared on CNN.