High Quality Content by WIKIPEDIA articles! A freshwater snail is one kind of freshwater mollusc, the other kind being freshwater clams and mussels, i.e. freshwater bivalves. Specifically a freshwater snail is a gastropod that lives in a watery non-marine (freshwater) habitat. The majority of freshwater gastropods have a shell, with very few exceptions. Some groups of snails that live in freshwater respire using gills. Others need to surface to breathe air.