Slate-pencil Urchin

Habitat:

Found singly, close to the bottom in crevices of the reef, over shallow waters amongst patch areas of rocks, rubble and seagrass of coral reefs. They feed nocturnally on corals and sponges. Widespread Atlantic Ocean, Caribbean, Mediterranean.

Notes:

Not the best photos but I don't think I've ever spotted this creature before (or if I have only once before.)