A substance thought to be a piece of rare, potentially valuable whale vomit has turned out to be a lump of rubber. Andrew Hughes found what he hoped was ambergris - produced in sperm whales' intestines - on Anglesey.
He hoped it could be worth many thousands of pounds to the perfume industry, although the value of ambergris is disputed.
Dr Vera Thoss, of Bangor University, conducted tests over two days and said it was "basically a lump of rubber".
News video from before the tests were concluded.
YouTube link. Original BBC News video.
Although unable to say exactly what the substance was, she said she believed it was probably a latex or runny rubber, which showed characteristics of being burned - possibly on a ship which caught fire.
Mr Hughes found the substance while looking for fishing bait with a friend at Porth Dafarch, near Trearddur Bay earlier this month.
But, after discovering the find was worthless, he said he could see the funny side of it.
"We weren't getting our hopes too high anyway because we're down to earth," he added.