Up to 5mm, rounded (but often quadrate in juveniles) but variable. Less tumid than other Euglesa species and often with a silky appearance. The umbo is flattened and off-centre.Best identified by examination of the cardinal teeth - part of the internal hinge.

Other Euglesa species.

All types of aquatic habitats.

All year.

Common and widespread across all of Great Britain and Ireland.

Probably common but under-recorded.