Winkle or Topshell ?

Winkle or Topshell ?

Observation - Winkle or Topshell ? - UK and Ireland. Description: Annual emptying of Thanet's largest tidal pool (at low tide end would be 5m) Found in sublittoral, submerged probably all of the time here, when the sluice gates are shut. This unusual coloured shell for ID please.

Annual emptying of Thanet's largest tidal pool (at low tide end would be 5m) Found in sublittoral, submerged probably all of the time here, when the sluice gates are shut. This unusual coloured shell for ID please.