Nerite snails, Nerite virginea, are small algae eating snails commonly found in shallow inshore waters around porites corals and on turtle grass blades. They come in a variety of shell colors and designs, but are commonly covered with coralline algae, so they\'re often pink.  These are not the species of nerite that live in the intertidal zone and crawl out of your tank, so you don't have to worry about finding them on the floor.  They are reef safe and will not bother any other invertebrates or fish.