Perspicaris an extinct genus of bivalved arthropod from the Cambrian period. Fossils have been found in North America, primarily the Burgess Shale of British Columbia, Canada but also possibly the Whe

The Marjum Formation is a Cambrian geological formation that overlies the Wheeler Shale in the House Range, Utah. It is named after its type locality, Marjum Pass, and was defined in 1908. The formati