A man walking his dog has discovered a ‘horrible smelling’ lump of sperm whale vomit thought to be worth around £100,000.

Ken Willman originally paid little attention to the dirty yellow rock his dog Madge dug up as the pair walked along Morecombe’s beach.

However, upon arriving home he says something “triggered my mind” and he looked the substance up on the internet.

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On doing so, unemployed Mr Willman discovered the substance is likely to be ambergris - a lump of sperm whale vomit – which is used in perfumes such as Chanel No.5 to amplify the scent.

The lump of vomit is often called ‘floating gold’ and is said to smell like old wood or fungus. It acts as a scent stabiliser when combined with other ingredients, however.

“It was like walking on the beach and finding a bag of £50,000 in cash,” Mr Willman said.

He added: “I didn't actually realise what it was at first, I couldn't understand why Madge was so interested in it. It smelled horrible."

Mr Willman went on: “I left it, came back home and looked it up on the internet. When I saw how much it could be worth, I went back to the beach and grabbed it.”

A French dealer has already offered Mr Wilman €50,000 (£43,000) to purchase the substance if it turns out to be ambergris, but it is believed it could be worth twice as much as that.

Mr Willman says he will be sending a small amount of the vomit to France to have it checked, and if it turns out to be ambergris it “could be like winning the lottery”.

Chris Hill, curator at the Aquarium of the Lakes in Cumbria, said: “It's quite a find…How much it's worth will depend on how fresh it is, but it's potentially $180,000.”

He added: “There are places in Europe that will buy it from you. They will age it, like a fine wine, and then test it for perfume.”

Ambergris is the intestinal slurry of a sperm whale which is usually ejected into the ocean when the animal has a stomach or throat problem.

It can float undiscovered for years, gradually hardening and developing its distinctive odour, usually washing up on beaches in small, fist or football-sized lumps.

In 2006 a couple walking on an Australian beach found a 32-pound chunk of ambergris, which netted them $295,000.