Parietal eye
![The parietal eye (very small grey oval between the regular eyes) of a juvenile bullfrog (Rana catesbeiana)](/Images/godic/202502/01/Frog_parietal_eye2316.JPG")
![Adult Carolina anole (Anolis carolinensis) clearly showing the parietal eye (small grey/clear oval) at the top of its head.](/Images/godic/202502/01/Anolis_carolinensis_parietal_eye2316.JPG")
![Parietal eye of the Merrem's Madagascar swift (Oplurus cyclurus) is surrounded by a big black-and-white spot on the skin, giving it the](/Images/godic/202502/01/Madagascar_spiny_tailed_iguana_cropped2316.jpg")
A parietal eye, also known as a third eye or pineal eye, is a part of the epithalamus present in some animal species. The eye is photoreceptive and is associated with the pineal gland, regulating circadian rhythmicity and hormone production for thermoregulation.