As denoted by the scientific name of this group of opisthobranchs, they are separated from the others by their head shield.

Several species of the group have heavy, spiraled external shells while several others have thinner globose shells with a wide aperture. The former are capable of withdrawing into the shell, while the latter are not. In these, also, the shell is generally partially hidden within the mantle.  

Generally speaking the cephalaspideans are burrowers, feeding on foraminiferans, polycheate worms, and bivalves. They spend most of their life just beneath the surface of the sand or mud, hence their rather dull coloration. Several species are voracious carnivores which feed on relatively fast moving food.