Ten-Lined Urchin

Eucidaris metularia is a primitive species of sea urchin and comes from an ancient lineage that has hardly changed over the past 150 million years. The test is robust and somewhat flattened and up to 3 cm (1.2 in) in diameter. The ambulacra are almost straight and have horizontal pairs of pores. The primary spines are few in number, stout with a truncated tip and distinctively banded. The secondary spines surround the primaries and are more numerous, much smaller and flattened.

Eucidaris metularia is found in shallow parts of the Indo-Pacific Ocean. Its range includes the Red Sea, East Africa, Madagascar, the Seychelles, Aldabra and Chagos and extends as far east as Fiji, Hawaii, Japan, and northern Australia. It is a common species among seagrasses and in rocky back-reef lagoons, usually in shallow water, but sometimes at depths of down to 500 metres (1,600 ft). It also occurs under rocks and in crevices.