All these groups tend to be radially symmetric and have a water vascular system that operates by hydrostatic pressure, enabling them to move around by use of many suckers known as tube feet.

At the posterior, inside the body cavity, there are a bundle of Cuvierian tubules or cotton glands which can be ejected as a tangle of sticky white threads to confuse or enmesh predators.

When feeding, it bends its body down towards the substrate, presses the ring of oral papillae against the surface and opens its mouth wide.

It then extends and retracts its short tentacles repeatedly and "vacuums" up sediment, extracts the nutritious part and deposits the unmetabolised portion as a sausage-like string of droppings.

Juveniles are seldom seen so it is surmised that they live by day in crevices and under rocks for protection from predators whereas the adults take no particular care to remain hidden.