Nudibranch

Nudibranchs are shell-less marine gastropods whose forms range from broad, smooth bodies to animals covered in slender projections. Sensory structures on the head help them detect chemical information. Many species specialize on particular prey, and some obtain defensive chemicals or stinging cells from their food. Bright colors can signal defenses, though not every species is conspicuous. The name covers many different sea slugs rather than a single species with one fixed pattern.