Sphaerechinus granularis Purple Sea-Urchin Sea Hedgehog Echinoderma Echinozoa Echinoidea Regularia Toxopneustidae

Sphaerechinus granularis Violet Sea Urchin cm 4.5-6.5  Sea Hedgehog Echinoderma Echinozoa Echinoidea Regularia Toxopneustidae.
Family: Toxopneustidae.
Common name: Violet Sea Uchin or Purple Sea Urchin.
Syn. Echinus albidus, Echinus brevispinosus, Echinus granularis, Echinus dubius, Echinus subglobiformis, Sphaerechinus brevispinosus, Sphærechinus ovarius, Sphaerechinus roseus, Strongylocentrotus granularis, Toxopneustes brevispinosus.

Sphaerechinus granularis is a species of sea urchin in the family Toxopneustidae, commonly known as the purple sea urchin, or sometimes purple sea urchin (although the latter is also a common name for a Pacific sea urchin Strongylocentrotus purpuratus). Its range includes the Mediterranean Sea and the eastern Atlantic Ocean.
There are two distinct color forms. The dermalskeleton is purple in both, but one has purple spines and the other white. The spines are short and blunt, all of the same length and arranged neatly in rows.
S. granularis prefers sheltered places and lives on algae-covered rocks or gravelly substrates. It is usually found in the neritic zone up to about 30 meters, but occasionally reaches 130 meters. It is also found in the Posidonia oceanica meadows.
S. granularis often becomes covered in bits of algae and shell fragments, which are held in place by tube feet and claw-like structures known as pedicellaria. It feeds on algae, in particular encrusting coralline algae, blades of marine phanerogams and their epiphytic organisms and debris.
In Tunisia S. granularis lives in association with two other species of sea urchins, Centrostephanus longispinus and Paracentrotus lividus. It is preyed upon by starfish.