34 Nucella lapillus. Shell height 31.4mm. Mouth of Mersey Estuary, England. July 2014.

34 Nucella lapillus. Shell height 31.4mm. Mouth of Mersey Estuary, England. July 2014.

Strong white columellar muscle attaches opercular disc to columella of shell. Pale outer layer of operculum being extruded from opercular groove on anterior of opercular disc (pointing to posterior in image as foot folded).