Setosella vulnerata (Busk, 1860)

General description: 

Setosella vulnerata is an encrusting bryozoan. Colonies form very small sub-circular patches, which are white in colour. Autozooids are oval and range in size from 0.3-0.38 by  0.2 mm.

The species is able to colonise shell fragments, small pebbles or gravel. It occurs in subtidal waters, most frequently between 30 to 100 metres, but it has also been recorded from as deep as 3700 m.
Setosella vulnerata occurs in the eastern temperate Atlantic from Norway, Shetland and the North Sea to Madeira and the Mediterranean. It is widely distributed around the British Isles.