Diadema of Cyrene

Cyrene Reef has lots of these large black Diadema sea urchins with long poky spines!

Here's some we saw today.

There was one perched on a bit of coral rubble with long spines (relative to the body).Here is a closer look at the upperside. You can see it has faint bands on some of the spines.Its underside was dark.There was another one with long banded spines.Here's a closer look at the upperside.The underside was pale.And in a deep pool full of seagrasses, we encountered two enormous ones! They were as big as my face.
They had shorter spines (compared to the body). Here's a closer look at the upperside.And the underside.All of them had an orange ring around the bulbous anal cone, white spots and blue lines; all these characteristics of varying boldness.

To be absolutely sure of what species they are we would need to take a specimen and have an expert examine the small features on their skeleton (see Test of Urchin).

But meanwhile, it's good to have an open mind and document all the Diadema we see, and observe their differences and similarities.