Story highlights A couple in the UK could get $70,000 for suspected "whale vomit" found on a beach

Ambergris is a rare substance that makes perfumes last longer on the skin

(CNN) If you happen to come across a smelly rock while taking a long walk on the beach, it could be your lucky day.

A couple in the UK stumbled across a large rock that many are calling "whale vomit." The "rock" could be ambergris, which is a rare substance used to make perfumes last longer on the skin.

"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."

Gary and Angela Williams followed a pungent smell while walking on Middleton Sands beach near Morecambe Bay that led them to what they believe to be a large lump of ambergris.

"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.

Couple stunned after stumbling across chunk of WHALE VOMIT on beach - and it could be worth £50,000 pic.twitter.com/SF2Jb7T8UT — Ｈｅａｔｈｅｒ (@itsrealH) April 13, 2016

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