Tank crew standing in front of M-4 tank, Ft. Knox, Kentucky, June, 1942. (Alfred Palmer/OWI/LOC)

Veteran cholita wrestler Jennifer dos Caras, 45, holds a cement block over teen wrestler Lucero la Bonita in the ring in El Alto, Bolivia, Monday, January 21, 2019. Trainees of cholita wrestling are still a year away from their full professional debuts while competing in matches against established athletes. (Photo by Juan Karita/AP Photo)

A reveler in costume laughs during the “Cordao do Boitata” street party in Rio de Janeiro, Brazil, Sunday, February 24, 2019, one of the many parades before the official start of Carnival on March 1. (Photo by Leo Correa/AP Photo)

A man with a cap on his face sleeps on a floor at the Mahabat Khan Mosque in Peshawar, Pakistan on March 4, 2019. (Photo by Fayaz Aziz/Reuters)

“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)

This is the moment a diver appears to shake hands with a giant 52ft whale. The divers were just metres away when one humpback whale – which weighs 36,000kg – extends its giant flipper in a peaceful manner. (Photo by Masa Ushioda/SeaPics/Solent News & Photo Agency)

A curious leopard cub toys with a camera at MalaMala Game Reserve in Mpumalanga Province, South Africa. (Photo by Barcroft Media)