These creviced rocks exposed to strong waves on the north coast of Anglesey are well suited to M. neritoides but only a single specimen was found here in careful search in 2013.  Absence or extreme scarcity on this coast was noted in Lewis (1964). It is well established on the western coast of Anglesey where sea water is warmer in winter, and absent or extremely scarce further north on the east coast of the Irish Sea. Frequent misidentification of Littorina saxatilis/arcana probably accounts for records further north in the NE Irish Sea such as those on NBN Atlas from unsuitable sheltered salting habitat on the Solway coast, Scotland.