Twisted Ramshorn - Bathyomphalus contortus

Up to 6mm and 2mm thick with numerous tight whorls and an crescent-shaped aperture which partly wraps around the last whorl. It is noticeable concave on one side and more or less flat on the other. The shell has a rounded edge profile and has radial growth lines.

Usually lives in still water such as lakes, ponds and ditches, preferring well vegetated habitats. It can be found in the backwaters of rivers. The species is generally tolerant of pollution and nutrient enrichment.

All year.

Common and widespread.

Uncommon but probably under-recorded.