Coastal excavators

Nick Baker (Hidden Britain, August 2017) mentions that a number of ‘boring molluscs’ may be the cause of holey rock on the seashore and then describes Pholas dactylus. The reader may assume that Pholas is the only molluscan cause of holes in rock. However, in Collins Pocket Guide to the Sea Shore, J Barrett and C Yonge give an excellent summary of the wide variety of marine organisms that bore into rock, including Hiatella (Saxicava) gallicana, which is probably the commonest on our coasts.