"Pioche Formation" Crossing the lower-middle Cambrian boundary, the Pioche Formation in eastern Nevada (USA) contains common remains of trilobites and soft-bodied ecdysozoan taxa. These fossils provide important information about the nature and variety of Cambrian ecosystem. Olenelloid trilobites (center of diorama) were extremely abundant in this environment and other arthropods like Canadaspis, worm Opabinia, sponges, and algae (Margareta genus) are also found. Media: Adobe Photoshop. Click on arrows to get closer or view next illustration.