Its poison is hidden in hollow spines among its hairs.

Other distinguishing characteristics include hollow spines tipped with hoof-like structures and simple mouthparts.

This is due to the hollow spine and rails of the track, which are known to produce a roaring sound.

Unlike most other sea urchins, they generally have hollow spines.

Members of this order are distinguished from other sea urchins by the combination of a flexible test and hollow spines.

It is a typical sea urchin, with extremely long, hollow spines that are mildly venomous.

The larvae are covered in hollow spines that are attached to a poison sac.

Its spire is low and the body whorl has six or seven varices, each varix forming two long, hollow spines.

The hollow spines suck essential juices from the creatures the plant impales, and also rainwater.

The poison is hidden in hollow spines among the hairs.