Black sea urchin

It is a rather big and strong regular sea urchin. The spines are robust and sharp, black with sometimes a blue-greenish tinge (depending on the light). They can be recognized thanks to the 5 grey sutures on the upper face, exhibiting distinctive zig-zag pattern. The oral face is clearer. The juveniles are clearer too (they can be black but also pale brown), and often show strikingly asymmetrical spines, due to their habit to use them for digging hiding holes in soft rocks. They can be confused with the Diadematidae sea urchins which sho longer and more slender spines, with an anal papilla, or with Echinometra mathaei, which also digs holes but is smaller, with shorter spines and never truly black.