Sidneyia inexpectans

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

Very rare Burgess Shale predatory arthropod and one of the largest animals known from the site. Gut contents from some specimens show that they fed on hyolithids, small crustaceans and trilobites. This huge specimen is 110mm (4.3 inches) on a 150mm slab from a collection made over 60 years ago. No restoration, no repair.