Measuring 0.5 - 1.5 cm long, they are transparent in their first year with 3 irridescent blue lines running aross the lenth of the shell. The adult stage has a darker shell and the blue 'rays' are still visible. On kelp, the limpets feed using their radula - a tongue covered in teeth - to rasp and graze the seaweed, leaving small depressions. The limpets are lost in the autumn when the seaweed sheds its fronds.
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