“In anatomy, heterochromia refers to a difference in coloration, usually of the iris (but also of hair or skin). Although infrequently seen in humans, complete heterochromia is more frequently observed in other species, where it almost always involves one blue eye”. – Wikipedia (Photo by StooMathiesen)

Bottlenose dolphins swim over visitors in water tank at the Hakkeijima Sea Paradise aquarium-amusement park complex in Yokohama, southwest of Tokyo, Tuesday, July 21, 2015. Temperatures in Tokyo's metropolitan area neared around 96 degree Fahrenheit, or 35 degree Celsius, on Tuesday. (Photo by Shuji Kajiyama/AP Photo)

Mutant vehicles on the Playa are seen as approximately 70,000 people from all over the world gather for the 30th annual Burning Man arts and music festival in the Black Rock Desert of Nevada, U.S. September 3, 2016. (Photo by Jim Urquhart/Reuters)

A woman prays as she touches the carcass of a male elephant after he, according to forest officials, was electrocuted early morning in a paddy field on the outskirts of Guwahati, India, June 20, 2017. (Photo by Anuwar Hazarika/Reuters)

Japanese chorus girls appear to be drilling in military tactics atop their theater building as they perform salutes, June 30, 1937. The officer is from the Japanese regular army and says the girls display more rhythm in their drills than do the regular troops. (Photo by AP Photo)

Elementary school sumo wrestlers compete in the sumo ring during the Wanpaku sumo-wrestling tournament in Tokyo, Japan July 30, 2017. (Photo by Kim Kyung-Hoon/Reuters)

People dance in a park on a foggy day in Huai'an, Jiangsu province, China October 10, 2017. (Photo by Reuters/China Stringer Network)

In this Saturday, December 30, 2017, picture a girl wearing a bear fur costume takes part in an annual bear parade in Comanesti, Romania. It's a tradition that originated in pre-Christian times, when dancers wearing colored costumes or animal furs went from house to house in villages, singing and dancing to ward off evil. (Photo by Vadim Ghirda/AP Photo)