Rotulidae

Rotulidae is a family of small sand dollars native to the Atlantic coast of Africa, with 3 genera, with Rotula and Heliophora being extant, the other, Rotuloidea, being extinct since the Pliocene, but all three being found in the fossil record along the Atlantic African coast since the Miocene.

==Morphology== The generalized rotulid has a circular to oval-shaped test, and indentations starting along the posterior edge. In Heliophora, the indentations may remain restricted to the posterior edge, or they may reach to the anterior edges of the test. Depending on the individual, the indentations may be very shallow, or very deep, forming very long "fingers," or digits. While rotulids are very distinctive in appearance, they are also highly morphic, with a tremendous diversity seen in individual specimens. That the digits are very fragile, and prone to breaking off and regenerating only adds to individual variations.