Ever heard of the scientific word "Clione Limacina". In another words, it is known as Sea Angel. It is neither a fish nor a jellyfish. It belongs to the Orthogastropoda, a subclass of Gastropoda.. which snails & slugs fall into this category. It's actually a jelly-like, shell-less sea snail., It is thus known as gymnosome which translates as "naked-body in latin.