Very high shells; height more than 70% of the length. High up the shore on rock that dries out for long periods at low water so limpet contracts its muscles to clamp firmly to the rock to prevent water loss. This pulls into a small diameter the mantle which forms the shell and results in a narrow tall shell. Shells eroded as exposed to acid rain for long periods. Left: apex 36% of L. from anterior, Llŷn Peninsula, Wales, September 2009. Right: Menai Strait, Wales, March 2010.