A British man has been offered $65,000 for a strange-smelling rock his dog found on a beach, which is likely a rare form of whale vomit used in perfumes, the BBC reports.
Ken Wilman was walking his dog Madge in the coastal town of Morecambe in northwest England when she began "poking at a rather large stone" with a waxy texture and yellowish colour.
At first he left it on the beach, but "something triggered in my mind", Wilman said, prompting him to go back and retrieve the object, which he believes is a piece of ambergris, a substance found in the digestive systems of sperm whales.
Whales sometimes spew up ambergris, which floats on water and has been highly prized for centuries. It is used in perfume-making for the musky fragrance it acquires as it ages but newer ambergris is foul-smelling.
"When I picked it up and smelled it I put it back down again and I thought 'urgh'," Wilman told the BBC.
"It has a musky smell, but the more you smell it the nicer the smell becomes."
He is waiting for tests to confirm his find is ambergris, nicknamed "floating gold", but says he has been offered $65,000 for it by a French dealer.
"It's worth so much because of its particular properties," Andrew Kitchener, principal curator of vertebrates at the National Museum of Scotland, told the broadcaster.
"It's a very important base for perfumes and it's hard to find any artificial substitute for it."
The substance gets a mention in the classic 1851 whaling novel Moby Dick, where author Herman Melville writes: "Who would think, then, that such fine ladies and gentlemen should regale themselves with an essence found in the inglorious bowels of a sick whale! Yet so it is."