Barnacle Bill The Sailor

Patella vulgata - Common limpet. Although they may seem to be fixed to the rock, common limpets actually move around to graze on algae during moist conditions or when they are submerged by the tide. They return to the same spot by following the mucus trail that they deposit. This spot becomes worn by the edges of the shell, and eventually an obvious 'scar' in the rock is created. This helps the limpet to attach even more tenaciously to the rock, a strategy that protects it from desiccation.