Canadaspis perfecta a bivalved arthropod also occurring in the Middle Cambrian Burgess Shale. As a Phyllocarid, it is one of the lesser know crustaceans from the Cambrian and also among the earliest animals with a hard shell casing. They had a fairly large carapace that sheltered the anterior part of the body. This structure hinged along the dorsal edge like a bivalve. Usually only the carapace is found. Rarely are the soft parts preserved in the Cambrian shale's of Utah. This is an extremely fine specimen.