Dendraster L. Agassiz ex Agassiz & Desor 1847的圖片

描述：

The aboral side of the shell (test) has the off-centered petalidium, as seen clearly here in a dead specimen which has lost its spines. Note also that, unlike urchins which have 5, sand dollars have only 4 gonopores, visible around the star-shaped pattern in the center.