What appears at first glance to be a dirty beach rock could turn up to be floating gold for a British man.
Ken Wilman, 50, told British media that he was walking on a beach with his dog, Madge, this week when they stumbled upon what could be a rare find.
The substance is a form of whale vomit, according to Metro.co.uk.
Whale vomit, called ambergris, is an ingredient that is in demand for use by the fragrance industry. High-end perfumes such as Chanel No. 5 are reported to use ambergris as an ingredient.
The sperm whale vomit is also used in spices and medicines.
Wilman says he has been offered 50,000 euros ($68,000 Canadian) from a French ambergris dealer.
According to the report, experts believe it could be worth much more once it has been officially verified.
The unusual stone, which had washed up on a beach in Morecambe, England, gives off a musky smell that has been likened to the smell of horse manure.
Wilman, a Lancashire resident, said the stone weighs three kilograms.
Chris Hill, curator at the Aquarium of the Lakes in Cumbria, told the newspaper Metro.co.uk that it is quite a find.
"There are places in Europe that will buy it from you," Hill said. "They will age it, like a fine wine, and then test it for perfume."
Wilman said he intends to send the sample to an expert in France to verify it.
Sperm whales are known to eject the intestinal fluid into the ocean, where it bobs along and eventually gets collected along shorelines.
Callum Roberts, a professor of marine conservation at the University of York, said the find appeared legitimate.
"It's a waxy, yellow-grey piece of flotsam," he told Associated Press. "I'm sure that 95 per cent of people would walk past it without further thought."
He praised Wilman's quick thinking, invoking the scientific dictum that "fortune favours the prepared mind."
With report from Metro.co.uk and Associated Press