Body thin, cylindrical.
Prostomium narrow, anteriorly weakly incised, with 2-8 irregular placed eyes; without antenna. Posteriorly with a caruncle that reaches the anterior margin of segment 2. Two long palps present.
Notopodial postchaetal lobes in the anterior region oval to finger-shaped, then wholly fused to the gills and behind the gills short and oval. Neuropodial postchaetal lobes of anterior segments oval, posteriorly broadly rounded (P. elegans-parapodium). All notopodia with capillary chaetae, anterior notopodia also with lanceolate chaetae. Anterior neuropodia with capillary chaetae. 8th or 9th and following neuropodia with 4-5 bent hooded hooks (P. elegans-chaetae).
Gills start at chaetiger 11-20. In females 7-9 pairs, in males 20-28 pairs. Males also with a pair of cirri or gills on the second chaetiger.
Pygidium with 4 pointed and papillated lobes.
Up to 15 mm for 60 segments.
Yellowish, anteriorly greenish.
From mid-shore to sublittoral, in rock crevices and old shells; also in brackish water.
Whole North Sea, Skagerrak, Kattegat, Öresund, Baltic Sea, North Pacific, North Atlantic to Mediterranean, Black Sea, Arctic, South Africa and Australia.