Colonies attached; branching profusely and irregularly, mostly in one plane - fan-shaped, hence the common name, sea-fan - although occasionally more bushy forms occur; height up to 300 mm, breadth to 400 mm. Polyps close set and irregularly arranged on the branches although tending to lie in the plane of branching. They are retractile within protruding, eight-lobed calyces. Spindles from inner layer of rind up to 0.2 mm long, balloon clubs from outer layer about 0.05 mm long.
Colouration: Colour of flesh varies from white or yellowish to deep orange-pink; axis glossy black or dark brown.
On rocks, particularly on vertical or overhanging surfaces, in depths of l0-200 m. Colonies are usually, but not invariably, oriented across the prevailing water currents.
South and west coasts of the British Isles. Older records suggest that this species occurred in the English channel almost to the Thames estuary (Margate) but its present eastward limits are unknown; northward it extends at least to northern Ireland and perhaps to west Scotland. Outside the British area it is common around south-west Europe, in the Mediterranean, and the north-west coast of Africa.