Omalonyx

Omalonyx is a genus of air-breathing freshwater snails, pulmonate gastropod mollusks in the family Planorbidae, the ram's horn snails and their allies.

These snails are found in Central and South America. They are characterized by a flattened, limpet-like shell that allows them to adhere tightly to surfaces in flowing water habitats. This adaptation helps them resist being swept away by currents.

Omalonyx snails graze on algae and detritus, playing a role in the ecosystem of the streams and rivers they inhabit. Due to their sensitivity to water quality, they can be considered bioindicators of pollution. The taxonomy and exact species delineation within the Omalonyx genus can be complex and subject to revision.