Ptychagnostus praecurrens
Trilobite
Middle Cambrian
Burgess Shale, Stephens Formation
Field, British Columbia, Canada

7mm trilobite on 65mm slab. Rare.

Ptychagnostus is a trilobite genus known from the Middle Cambrian of numerous sites worldwide.  It’s been found on all continents, including Antarctica, but not Africa.  It seems to be everywhere but few specimens have reached the market.