This sea urchin is rather rare to find in the Aegean or the Mediterranean sea... These have shorter, thicker spines that are mostly dark purple in color with their tips commonly whitish, and they are far more heavier and also larger than the 'regular' urchins in the Mediterranean or the Aegean. These latter urchins (which I haven't scanned here) are black on the spines, and the spines are thinner and a little bit longer...