Find the word definition

Wikipedia
Megistaspis

Megistaspis is a genus of trilobites in the order Asaphida, family Asaphidae.

They lived in the Ordovician period (488.3-443.7 million years ago), from the Upper Tremadocian age until the Lower Llanvim age. These arthropods were a low-level epifauna, fast-moving and detritivore.