Body short and thick, somewhat narrowing in the mid-body region. Posterior end of body with two calcareous plates on the ventral surface. The margins of the plates are lined by bundles of long capillary chaetae. There are three half rings of stronger chaetae on each side of the anterior end. The long, thread-like gills are placed in two bundles dorsally at the posterior end of the body (Sternaspidae).
The following taxa of this family occur in the region: