Helicoplacus gilberti
Early Cambrian
Poleta Formation
White Mountains, Inyo County, CA, USA

Large 25mm on 47mm slab (r5)

Helicoplacus is a genus of early echinoderms of the Class Helicoplacoidea.  Isolated plates of helicoplacoids have been found at a few different sites around the world but the group is known from complete specimens at this locality.

It seems the helicoplacoids appeared during the Early Cambrian and died out before the Middle Cambrian.

See: Helicoplacoidea (opens in a new window)