Body long, cylindrical, with up to 90 segments.
Prostomium a sharp cone, without eyes, fused to the anterior segments. Anterior three achaetous segments more or less fused, often dorsally bi-annulated. One pair of grooved palps on the last achaetous segment or the anterior edge of the first chaetiger.
Long filamentous gills start at the last achaetous segment or the first chaetiger, just behind the palps, absent in posterior segments.
Anterior segments with long capillary chaetae; mid-body parapodia with long chaetae dorsally and ventrally thicker capillaries and spines; posterior segments with many thick spines in a nearly complete ring around the segments.
Up to 25 mm for 90 segments.
Bright or dark grey, brownish- or bluish-black.
On muddy bottoms in the shallow sublittoral.
Whole North Sea, Skagerrak, Kattegat to Baltic Sea, Arctic to Mediterranean.