Diameter of base up to 60 mm, height to 50 mm.
Base broad, usually wider than the disc, moderately adherent. Column variable in shape but typically tapers inward from the limbus, flaring out a little just below the disc. It is not divided into regions but in partial contraction often exhibits a parapet-like fold at the margin; in contraction it forms a hemisphere of firm consistency.
Tentacles: Tentacles short to moderate, their distinctive arrangement (see definition Genus Stomphia) being easily observed in expanded specimens; probably their fullest development is 6 + 12 + 18 + 36 = 72. If less than 12 tentacles are present in the second cycle, those adjacent to a directive are lacking. In life the six primary tentacles typically point inward over the mouth.
Colouration: Column red, orange, white, yellowish or brown, usually blotched irregularly with red, the general colouration often strongly resembling that of Urticina eques and other anemones of typically offshore occurrence. Disc translucent, grey, orange or yellow, with the mesenteric insertions indicated by red lines, lips of actinopharynx orange or red. Tentacles coloured like the disc, usually with two red bands and a median spot of white near the base; a similar white spot is often present on each endocoelic radius. This simple pattern may be partly or completely absent, specimens with a plain orange disc and tentacles being frequent.
Attached to stones or shells, with a definite preference for the large mussel Modiolus; always offshore in depths from 10 m down to at least 400 m.
A widespread, boreal-arctic species occurring throughout the circumpolar regions of the northern hemisphere; recorded from all British coasts except the extreme south.
Some species of this genus are well-known for their swimming ability but in S. coccinea the term swimming is something of an exaggeration. In response to contact with certain starfish (Echinodermata), or the nudibranch Aeolidia papillosa, the anemone releases its hold on the substratum and performs jerky flexions of its extended column; these actions may cause it to jump clear of the substratum, but only momentarily.