It smells like horse manure and looks like a dirty beach rock but this lump of ‘floating gold’ could pocket one man over £100,000.

The unusual ‘stone’ is believed to be a piece of rare and valuable whale vomit, or ambergris, an in-demand ingredient used in perfumes such as Chanel No.5.

Lancashire resident Ken Wilman discovered the 3kg lump while out walking his boxer dog Madge on Morecambe beach.

‘I didn’t actually realise what it was at first, I couldn’t understand why Madge was so interested in it,’ he explained. ‘It smelled horrible.’

‘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!’

Mr Wilman has already been offered $50,000 (£42,000) for his find by a French ambergris dealer, but experts believe it could be worth much more once it has been officially verified.