What is "phacops"

Phacops \Pha"cops\, n. [NL., fr. Gr. ? a lentil + ?, ?, the eye.] (Paleon.) A genus of trilobites found in the Silurian and Devonian formations. Phacops bufo is one of the most common species.

Phacops is a genus of trilobite in the order Phacopida, family Phacopidae, that lived in Europe, northwestern Africa, North America and China from the early until the very end of the Devonian. It was a rounded animal, with a globose head and large eyes, and probably fed on detritus. Phacops is often found rolled up, a biological defense mechanism that is widespread among smaller trilobites but further perfected in this genus.