Description
Heart urchins have a star-shaped groove on the dorsal side. The front has a deep notch and is flattened, the back round. This animal lives most of his life burried in the sand just below the surface. The spines are not only means of defense but are also digging aids. The food consists of debris and organisms, that are brought to the mouth with it's tube feet. The anus is positioned in the back of the ventral side and just like the mouth, it is surrounded with longer spines. Reproduction takes place when females and males relaese their sperm and eggs into the water. The biggest enemy is the Spiny starfish (Marthasterias glacialis).

Size
This animal can reach lengths of about 120 mm.

Colour
Colour can range from lilac to pink.

Habitat
In sand, gravel and mud floors from the shallow zone to about 900 meters deep.

Distribution
North Atlantic Ocean and the entire Mediterranean.