Clausiliacea

The Clausiliacea are a superfamily of terrestrial snails belonging to the subclass Pulmonata. These snails are characterized by their elongated, sinistral (left-handed) spiral shells. A unique feature of the Clausiliidae family within this superfamily is the presence of a rod-like structure called a clausilium, which functions as an operculum, a sort of door to seal the shell opening.12

This superfamily is primarily found in Eurasia and South America. The classification of gastropods, including Clausiliacea, has undergone significant revision, with ongoing research utilizing both traditional anatomical studies and molecular data to understand their evolutionary relationships.3