What is "phreatodrobia"

Phreatodrobia is a genus of very small or minute freshwater snails with a gill and an operculum, aquatic gastropod mollusks in the family Lithoglyphidae.

The generic name Phreatodrobia is derived from the Greek word " phreatos" which means ground water, as in phreatic, and from the suffix -drobia based on family name Hydrobiidae (where it was originally classified), which means "living in water".