A cladogram of nonchordate invertebrates from single-celled animal ancestor to chordates depicts evolutionary relationships among major groups of animals, like Sponges, Cnidarians, Arthropods, Roundworms, Flatworms, Annelids, Mallusks, and Echinoderms. During the evolution, the following important traits are evolved: Radial symmetry Three germ layers, bilateral symmetry Tissues Multicellularity Protostome development Deuterostome development