Ambergris

From a story in the Bournemouth Daily Echo:

A schoolboy has stumbled across a rare piece of [ambergris] which could be worth £40,000... the substance is highly sought after and is used to prolong the scent of perfume. Eight-year-old Charlie Naysmith made the discovery at Hengistbury Head near Bournemouth in Dorset, much to the amazement of his parents.

His find doesn’t look very exciting and most people would probably walk straight past it, mistaking it for a stone. But Charlie was curious enough to pick it up and, after a bit of research, he and his family discovered it is worth between £10,000 and £40,000...

See also This wasn't used to poison Charles II.

Via Nothing to do with Arbroath.