The Cambrian period of the Paleozoic Era, beginning 545 mya, exhibited an amazing diversity of life forms preserved in the Burgess Shale, a deep water marine deposit from the Mid Cambrian of British Columbia, Canada. This scene shows the enormous variety of invertebrates, most notably the arthropods (trilobites, Marella). Marine worms (Ottoia), echinoderms, sponges, and the aggressive predatory Anomalocaris are also pictured.