The Common Sea Slug (Aeolidia papillosa), also known as the Sea Mouse is a strange looking creature. It round, tapering body is covered in small, fine cerata (tentacles) which give it a furry appearance which is compared to a mouse or other small mammal. They have larger tentacles located on their head and the colour can range from reddish to grey, purple or blue. They overall length of this species is a maximum of 10 to 15cm.
They can be found at a range of depths from the intertidal zone to several hundred metres deep. They are most commonly found along the western coast of the British Isles, with their range extending to parts of the Atlantic and Pacific Oceans. With the limited mobility this species displays they are thought to concentrate on feeding on sea anemones. Small sea anemones will be consumed whole, but with larger anemones only the tentacles will be eaten.