DESCRIPTION: Reaching up to 10mm in diameter this barnacle is best recognised by its 4 calcified plates, the low and conical shape and the opercular aperture that is diamond-shaped. When young the plates are smooth, older plates have marked vertical ridges. Colour starts off as an opalescent grey-white before becoming grey-brown. Many specimens tend to have a slightly 'inclined' position. DISTRIBUTION: Found around the coasts of England and Wales with a few records from Scotland and Ireland. HABITAT: Found primarily on  mid-shore rocks but can extend to shallow sublittoral zones. It is a species that doesn't like exposed areas. BEST TIME TO SEE: All year round.