In addition to sponges, Placozoa has no symmetry and was often considered a “missing link” between protists and multicellular animals. Extant phyla in these rocks include molluscs, brachiopods, onychophorans, tardigrades, arthropods, echinoderms and hemichordates, along with numerous now-extinct forms such as the predatory Anomalocaris. The first body fossils of animals appear in the Ediacaran, represented …