A parietal eye, also known as a third eye or pineal eye, is a part of the epithalamus present in some vertebrates. It is located at the top of the head and is photoreceptive, meaning that it can sense light. The parietal eye regulates circadian rhythmicity and hormone production for thermoregulation. What is the parietal eye? The parietal eye is a small, vestigial organ … [Read more...] about The Parietal Eye: A Third Eye for Some Vertebrates