Nudibranchs are oval molluscs usually seen crawling very slowly along the seabed.
The truth is, they are flashy slugs which will eat anything going, and take hours over their hermaphroditic copulations. Then it turned into a carnivore, sloughed its armour and acquired a new set of biological and chemical defences. Today this shell-less snail is a highly sophisticated organism. There are at least 3000 known species of nudibranch worldwide, with a cluster of 900 in the South Pacific and approximately 130 in the Mediterranean and Atlantic. Identification and classification is not easy.