The reef sea urchin is black with spines up to a foot long as well as shorter spines. It has a red ring around the anus and a white spot over each genital pore.
The German scientist Nathanael Gottfried Leske classified the reef sea urchin in 1778 as being a member of the species Diadema setosum. It belongs to the class Echinoidea and the family Diadematidae.
Other common names for the reef sea urchin are black long spine urchin and long spine sea urchin.