A barman was stunned after discovering that a bizarre yellow lump he found a year ago could be whale vomit worth almost half a million dollars.

Boonyos Tala-upara, 44, picked up the mystery blob while walking along a beach on the island of Koh Samui in southern Thailand in June last year.

He kept it in his back garden and forgot about it. But when a friend visited last month they told him it looked like the highly valuable whale vomit, ambergris, sought after by perfume makers.

Boonyos is now hoping to sell the 22lbs wax-like structure for 500,000USD – an estimate based on previous finds around the world.

The bar owner said: ''The lump is large and golden with a waxy texture like melting candles. But it’s soft when I poke it, not like a candle.

''I tried burning some of it with a lighter, it changed into oil and then it went hard again. I have never seen anything like this before.

''This could be like a lucky lottery ticket for me. I want to sell it and retire.''

Boonyos said he had now shown the lump to friends and family who all agreed that it was a precious whale vomit.

''My sister living in Austria once told me the story about this thing that it was rarely found on the coast. I looked for more information on the internet and it was really similar to a whale vomit,'' he added.

Assistant Professor Thon Thamrongnawasawat, Vice Chancellor of Faculty of Fisheries at Kasetsart University, said that there was a strong possibility that it was a whale vomit.