Bilateral symmetry, also known as plane symmetry, is symmetry that divided an animal into two roughly mirror image halves along the sagittal plane. This means that the organism is divided into a left and right half. Most animals have are bilaterally symmetric. Bilateral symmetry is even found in some of the simpler phyla. One unique phyla with respect to bilateral symmetry is Echinodermata, which includes starfish and sea urchins. In larval stage they have bilateral symmetry, but at adulthood they have five-fold radial symmetry. Bilateral symmetry is so abundant partly because of balancing limbs, and sensory organs to view as much as the animal can.