[2] Species of the genus Omalonyx occur in the Caribbean Islands, and they are also amply distributed throughout South America.

[2] The mantle covers the visceral mass and the edge of the shell.

[2] The species of Omalonyx are reported on macrophytes or emergent vegetation in the banks of lagoons, river floodplains, and streams.

[2] Omalonyx convexus lives in both clean and polluted freshwater environments, as well as on natural and artificial substrates.

[2] These snails are herbivorous, feeding on living plant tissues.