This is the largest of the British sea-pens, having been recorded up to 2100 mm in length. Ratio of stalk to rachis about 1: 5. Autozooids irregularly arranged or tending to form oblique rows, retractile within toothed calyces.
Colouration: Colour of flesh white, yellowish, or pale pink, autozooids often pink or red; axis white, with a characteristically shaped cross-section.
In muddy substrata from 20 to 2300 m depth.
Frequent around north and west coasts of Scotland and Ireland. Common throughout the North Atlantic; specimens referred to this species have been described from Madagascar, Japan, and New Zealand, thus its range could be worldwide.