Country diary: Slugs? Dull? This one is pure showbiz | Charlie Elder

Falmouth, Cornwall: The rainbow sea slug is a bizarre and breathtaking animal, and with warming seas it’s gaining a toehold in the south-west I have never seen a species quite so flamboyant in appearance.

A couple of centimetres in length, it was curled beneath the submerged rock like a piece of gaudy costume jewellery. When the cry went up that one had been found, I had to prevent myself from breaking into a run as…