Body quite short, broad; upper surface covered with numerous papillae, which are encrusted with mud and sand.
Prostomium rounded quadrangular to semicircular, with four blackish eyes with lenses, in one line, and 2 ocelli. Palps semicircular as long as the prostomium, broad only divided by a lateral groove. Lateral antennae flask-shaped, about as long as the prostomium. Median antenna a little longer than lateral ones.
Tentacular cirri and dorsal cirri as lateral antennae in size and shape, as long as the parapodial lobes or shorter.
Dorsal cirri flask-shaped, absent on second parapodium. Ventral cirri shorter than parapodial lobes. Aciculae present. Blades of compound chaetae moderate long and short, unidentate. All parapodia with one S-shaped upper unidentate simple chaeta (S. erinaceus-detail).
Pygidium with 2 flask-shaped anal cirri, slightly longer than dorsal cirri.
Proboscis with one big tooth.
Body up to 5 mm long for 22-37 segments.
Transparent to yellowish-white.
Amongst other evertebrates, holdfasts of brown algae and on various kinds of soft bottoms.
Probably cosmopolitan, English Channel, Skagerrak.