Quiz: Remember the definition of mal de mer?
any snail of the subclass Prosobranchia, class Gastropoda. Most of these primitive snails are marine; a few live on land or in fresh water. Many prosobranchs breathe by means of gills, which are located in front of the heart; some have a special respiratory structure on the mantle or, in land species, a simple pulmonary cavity. The auricle of the heart is in front of the ventricle. Larval torsion results in a figure-eight arrangement of the viscera and nerve cord that persists throughout life. Most species have a lid (operculum) on the foot that closes the shell when the animal retracts. The sexes are separate