Diadema
needle spined urchin
The needle spined urchin, Diadema sp., is very common at Julian Rocks. Diadema has long, thin, black needle spines. 
This it the empty test (shell) of the needle spined urchin. Blue gropers are known to feed on them.
They are often
found in groups in under rocks and in crevices. Family = Diadematidae
Max size =
Distribution = widespread
