Neritimorpha is a clade of gastropod molluscs that contains around 2,000 extant species of sea snails, limpets, freshwater snails, land snails and slugs. This clade used to be known as the superorder
Shells of the freshwater snail Theodoxus danubialis
Shells of the land snail species Helicina rostrata
Helicinoidea is a taxonomic superfamily of land snails that have an operculum. In other words, they are terrestrial operculate gastropod mollusks. They are in the order Cycloneritida and are quite clo