(O.F. Müller, 1771)
Body long and strong.
5-15 pairs of radioli. Radioli basally fused but not webbed, some with 1-8 eye spots. Peristomium with two eyes. Palps broad at their base, tapering to the tip. Collar with dorsal and ventral clefts and dorsolateral notches. Chaetiger 1 with 2 eyespots.
Thorax with 7-14 chaetigers; thoracic uncini with companion chaetae (P. reniformis-detail). Thoracic notopodial chaetae are long, straight with broad wings at each tip and short spatulate chaetae.
Abdomen with chaetae that are all bent capillaries, with broad wings; uncini similar to those on the thorax.
Pygidium with two papillae and eye spots.
Up to 120 mm for 300 chaetigers.
Horn-like, transparent, often spiralled, quite tough. Usually partly encrusted with mud or sand.
Body orange or red; crown white or pink with brown or violet bands or spots.
In crevices in rock or boring in limestone; on various kinds of substrata: shells, Laminaria , sponges or Lithothamnion ; lower shore and sublittoral, down to 600 m.
Widely distributed: Arctic, North Pacific, North Atlantic to Senegal, Mediterranean, northern North Sea to Bay of Kiel, Namibia, South Africa, Madagascar.