Canadaspis perfecta
Middle Cambrian
Burgess Shale, Stephens Formation
Field, British Columbia
Canada

Two specimens, 40mm and 26mm on 98mm x 32mm slab. Canadaspis has been the subject of debate ever since it was discovered. Walcott considered it a malacostracan crustacean, but modern work has grouped it with stem arthropods like Perspicaris. Note the preservation of the tail and other soft parts not normally found.