The Colourful World of Sea Slugs and Snails
When I think of a slug or a snail I think of slimy brown and grey creatures with or without shells that slide along thanks to their own mucous. Gross. But the slugs and snails that inhabit the waters of the world are a shocking array of colour and shapes so beautiful and unique they are the stuff of fairy tales. At least, I hope so because I will be putting these tiny creatures into my mermaid WIP.
First, let’s talk Nudibranchs. They’re mollusks or snails and they are the cutest, most colourful creature of the water I have learned about yet. They have these little tentacles on their heads and move in an undulating way that is hypnotising and relaxing.
Some of them are like tiny snakes, raising up to strike down their prey. They are just so cute!
They’re carnivores that live mostly in warm, tropical waters for their short lives. Nudibranchs can be tiny, less than an inch, or up to a foot long and weighing several pounds. 
My favourite so far are the Nembrotha Cristata Nudibranch. They have these lime green dots and a black body. I think of them as the goth Nudibranch.