Body of this scale-worm is of uniform width. Dorsal and ventral surfaces smooth.
Prostomium bilobed, with a peak on each lobe, median and lateral antennae papillate, and a pair of palps. Two pairs of eyes, the anterior pair below the prostomial peaks but visible from above, the posterior pair in front of the rear margin. First segment bearing chaetae and a pair of dorsal and ventral papillated tentacular cirri. Scales overlap, covering the body. The first pair of scales are round, the remainder kidney-shaped, margins fringed with papillae, the surfaces covered with small tubercles with bifid to 5 pointed tips. Notopodia are small mounds with a ventral acicular ligule and numerous chaetae. Notopodial chaetae are of 2 kinds: 1) stout with rows of spines and blunt tips; 2) capillaries, with fine tips. Neuropodia well developed with an anterodorsal ligule and chaetae in rows. Neuropodial chaetae with several rows of spines on the swollen terminal part and unidentate tips (G. cirrosa-detail).
Up to 50 mm for 38 chaetigers.
Pale yellow to brown, can be phosphorescent. Each scale has a small dark central patch.
Littoral to depths of 1000 m, often found in polychaete tubes, eg. Amphitrite , Chaetopterus , Thelepus or with bryozoans Melobesia or Amphihelia .
Arctic, North Pacific, North Atlantic, English Channel, whole North Sea, Skagerrak, Kattegat, Öresund and Belts up to Bay of Kiel.