Sternaspis scutata is a plump, whitish, barbell-shaped worm growing to a length of about 3.5 cm (1.4 in).

On the underside of the posterior part there are two hard brown chitinous plates forming a shield, the margins of which are rimmed with bundles of long chaetae.

[2] The range of S. scutata includes the Mediterranean Sea and the western Atlantic Ocean as far north as the English Channel; the type locality is the Gulf of İzmir on Turkey's west coast.

[4] This worm lives buried in the sediment with its head down and with its filamentary gills at the surface, presumably to enhance oxygen uptake.

It is a detritivore, scooping up and swallowing quantities of mud with its eversible pharynx, and absorbing nutrients as the bulk of material passes along the long, convoluted gut.