Wart Barnacle -"Verruca Stroemia" is a small grey box-like barnacle growing up to 1 cm in diameter.
This species is distinguished from other barnacles present in Britain and Ireland by its assymmetrical 4 plated shell wall, with strong interlocking sutures.
Instead of the paired moveable opercular valves of typical barnacles, half of the operculum is fixed to the substrate, while the other half forms a hinged 'lid'.
These very small barnacles are living amongst Bryozoa.
Location: Cave - Barafundle