[3] Deep water research was undertaken at Cap Blanc off Mauritania in West Africa, at depths between 1,000 and 2,000 metres (3,300 and 6,600 ft).

At 2,000 metres (6,600 ft), the seabed community, as sampled by trawling, was found to be dominated by Pourtalesia miranda and the Venus flytrap sea anemone (Actinoscyphia aurelia).

[4] At the greater depth of 4,000 metres (13,000 ft), these animals had given way to the foraminiferan Reticulammina labyrintha, with individual tests reaching 6 cm (2.4 in) in length.

In other parts of the abyss, live and dead sponges were the dominant lifeform; in general, the deeper the water, the fewer were the macrofauna present.

[4] A small commensal bivalve mollusc Axinodon symmetros was often found attached to the spines of the echinoid by byssal threads.