The ambulacral plates widen and form a petal-like pattern on the aboral surface, and it is through each of these areas that six to nine pairs of tube feet protrude.

Its range extends southwards from Iceland, Norway and Denmark to the Azores, Cape Bojador in Western Sahara, and the Mediterranean Sea.

[3] The spines are covered with fine, hair-like cilia, and are used to burrow or creep through the sediment while the animal searches for its food.

[4] It feeds on detritus, Foraminifera, diatoms and other edible particles, moving these with its tube feet to its mouth, where they are crushed by its jaws, and the organic matter is separated from the sediment.

[2] It is often found in association with such sea urchins as Spatangus purpureus and Psammechinus miliaris, the starfish Asterias rubens and the brittle star Ophiura albida.