Waptia fieldensis
Burgess Shale, Stephens Formation
Field, British Columbia, BC, Canada.

57mm with very prominent eye

Waptia is an extinct genus of arthropod that is shrimp-like in form but it is different enough that it hasn’t been classified within any family of crustacean nor any family of arthropods for that matter – another unsolved mystery of the Burgess Shale over 100 years after its discovery.  It does appear to be at least related to the ancestors of crustaceans.