Bilateral symmetry at some point in their life, three germ layers as embryos, are terrestrial, and are classified as protostomes. Bilateral symmetry at some point in their life, two germ layers as embryos, are aquatic, and are classified as protostomes. Radial symmetry at some point in their life, three germ layers as embryos, are aquatic, and are classified as protostomes. Bilateral symmetry at some point in their life, three germ layers as embryos, are aquatic, and are classified as deuterostomes. .