Rainbow sea slug found in Falmouth rock pool indicates warming sea

Sighting of rare animal - more often found in Spain, Portugal and France - in rock pool believed to be first in UK

Vicky Barlow was hoping to find a spider crab when she began poking around a rock pool on a beach in Falmouth.

But when she turned over a promising-looking stone, she was astonished to find something much rarer and much more colourful - a rainbow sea slug.