Trilobites

Agnostid

Agnostids are an odd little group of eyeless arthropods that have been traditionally lumped in with the trilobites. New research suggests they should probably be considred close relatives. These ones are mostly Itagnostus interstrictus, and are about 507 million years old, from the Wheeler Shales of Millard County, Utah.

The animals themselves are tiny, maybe 5-6mm, and the pieces of shale matrix vary but something like 9cm across.