Spiral keel follows the whorls. Keel and sutures overgrown with black mineral encrustation, so stout shell outline. Horny, translucent, oval, spirally-formed operculum; pale as on white opercular lobe, except where encrusted black.
Shell height 4.5 mm. Freshwater pool at top of salting, Dee Estuary, Cheshire. Sept. 2011.