On the buccal plates round the mouth on the underside are pedicellariae, defensive organs like minute pincers, each with two lateral teeth and one terminal tooth.

It is found off the coasts of Portugal, Spain, France, Belgium, the Netherlands, Denmark, Norway, Iceland, Sweden, the United Kingdom and Ireland.

[6] It has been recorded feeding on worms, barnacles, hydroids, tunicates, bryozoans, algae such as Laminaria spp., sludge and detritus.

[7] Spawning mainly occurs in the spring and a large female may release about 20 million eggs into the water column.

[9] Settlement mostly occurs in autumn and winter and the largest number of juvenile urchins was found at a greater depth than the kelp zone.