[2] Because of the difficulty in studying these echinothurioids at such depths, little is known of their feeding habits, but examination of their stomach contents suggests they eat detritus, mostly in the form of algal fragments.

Their reproduction is also relatively unstudied, but some members of the group, such as Phormosoma placenta, produce eggs with large yolks which at first rise towards the surface and later sink again.

The bilaterally symmetrical larva, called an echinopluteus, is planktonic and may not feed, relying on its yolk for nourishment before descending to the seabed and undergoing metamorphosis.

These are found infrequently because the test tends to disintegrate after the echinoderm dies and the only parts to be preserved are detached plates and spines.

Living members of the group were found after the Challenger expedition of 1872–76 began to explore the deep sea.