An Anglesey man has found what he believes to be a rare substance vomited by whales.
Andrew Hughes found what he thinks is ambergris, produced in the intestines of sperm whales, as he looked for fishing bait at Porth Dafarch near Trearddur Bay.
If it is the real thing it could be worth "tens of thousands of US dollars" a kilo, depending on the quality.
The yellow and black lump substance is used to produce perfume.
"We found it just by chance," said Mr Hughes, from Holyhead, who was out looking for bait with his friend Steven Burns at the high watermark after the recent bad weather.
"We went through a crevice looking for crab and found it.
Chemical analysis
"We thought 'Crikey is that ambergris?'
"We'd heard about it, but never actually seen it."
A chemical analysis is the only way to prove if the lump is actually ambergris.
Prof Michel Kaiser, of Bangor University's marine ecology department, said ambergris is a substance produced by sperm whales, which scientists currently believe is used to coat irritating objects in their intestines.
Objects like bones are coated in the waxy, oily substance and "discharged out of one end of the whale or the other".
He added: "My understand of ambergris is that it's used in the perfume industry to enhance the scent or prolong the duration with which the scent lasts.
"Of course, it is illegal to actually trade in the substance in countries such as the United States, but when ambergris is found washed up on the coast it's rather like treasure trove.
"Obviously the animal hasn't been killed illegally, it's just been discharged by the animal through a natural process."
Prof Kaiser studied the substance and said it "certainly seems to fit the description of what most people would describe as ambergris".
He added that internet searches revealed it could be worth "tens of thousands of US dollars" per kilogram, depending on its quality.
