Body slender, cylindrical, with up to 45 segments. Two regions of body are very distinct.
Prostomium is roundly conical with two small eyes and two nuchal organs.
Thorax with 9 chaetigers. First 6-7 segments with capillary chaetae only, 7th segment often with both capillary chaetae and long, slender hooded hooks and segment 8 and following segments with hooks only.
Abdomen with markedly longer segments.
The single genital pore between chaetigers 8 and 9 is surrounded by a pair of genital hooks on each segment in both sexes. (C. giardi-detail).
Pygidium is short, rounded, without cirri.
Up to 12.1 mm for 51 segments.
Pale pink to red-brown, in alcohol transparent.
Mud and muddy sand; between algae and Lithothamnion . From the eulittoral to the upper sublittoral.
North Atlantic, Aegean Sea, Black Sea, English Channel, North Sea, Skagerrak and Kattegat.