Shell damage and subsequent repair of the Antarctic limpet Nacella concinna was related to: 1) Boring algae combined with grazing activity of Nacella’s on these algae. This caused Nacella to produce extra calcareous deposits on the inside of the shell apex. 2) Tumbling of shells and impacts of rolling stones and ice blocs in the intertidal. This caused non-lethal damage of the shell margin which could be repaired. Up to 90 % of intertidal Nacella’s at exposed localities showed such shell repairs (see fig.). At a sheltered locality such repairs occurred at only 13% of the shells.