Clypeasteroids are considered radially symmetrical. However, they show slight bilateral symmetry because they tend to be slightly elongated, an adaption to facilitate movement through sediment. The bony ossicles of this species fuse together, forming a calcareous, disk-shaped shell or test. The test is covered with short, movable, densely-distributed spines that aid in movement though sand while feeding. The aboral surface bears five conspicuous flower petal-like structures, called petalloids. These are actually the ambulacral grooves. Each petalliod is equal in size and consists of two double rows of paired pores used in respiration. Petalloids also contain tube feet that function in respiration. Unlike tube feet seen elsewhere, they lack suckers at the ends and do not function in locomotion (Fox 1994). Clypeaster subdepressus is large, up to 300 millimeters in length. The oral surface is quite flat, with a slight concavity at the mouth. The test color ranges yellow to dark tan (Hendler, et al 1995).