Canadaspis perfecta a bivalved arthropod also occurring in the Middle Cambrian Burgess Shale. As a Phyllocarid, it is one of the lesser known 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. The type specimen of the genus is Canadaspis perfecta from the Burgess Shale of British Columbia, Canada (Briggs, 1978). Canadaspis are also known from the Pioche Shale of Nevada (Lieberman, 2003).

Also see: Utah Cambrian Explosion Fossils Phyllocarid Branchiocaris pretiosa from Utah Canadaspis laevigata Arthropod from Chengjiang

References:
Briggs, D, (1978) The Morphology, Mode of Life, and Affinities of Canadaspis Perfecta (Crustacea: Phyllocarida), Middle Cambrian, Burgess Shale, British Columbia. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences, Volume 281, Issue 984, pp. 439-487
Lieberman, A (2003) New Soft-Bodied Fauana: The Pioche Formation of Nevada. Journal of Paleontology. 77(4) 674-690.