Genus of freshwater snails with a modified limpetlike shell, giving them their common name river limpets.

Ancylus' lung-sacs always contain water, and they cannot breathe on land. They are found in springs, streams, and lakes adhering to stones and leaves.

Classification
Ancylus belongs to the family Limnaeidae, subclass Pulmonata, class Gastropoda; phylum Mollusca.