These adorable cats – which are twins – showcase their contrasting blue and green eyes. The cats have a condition called heterochromia iridis, which causes each eye to vary in color. (Photo by @sis.twins/Caters News Agency)

Iguazu Falls are waterfalls of the Iguazu River on the border of the Brazilian state of Paraná and the Argentinian province of Misiones. The falls divide the river into the upper and lower Iguazu. The Iguazu River rises near the city of Curitiba. It flows through Brazil for most of its course. Below its confluence with the San Antonio River, the Iguazu River forms the boundary between Argentina and Brazil.

In this March 14, 2015 photo, tourists take pictures from a viewing area at Iguazu Falls in Brazil. From walkways and bridges, viewers can count 270 water falls almost 100 meters (330 feet) high. (Photo by Jorge Saenz/AP Photo)

Conjoined twins Shivanath and Shivram Sahu have found a remarkable way to get to school – dropping to the floor and running like a spider.

Victoria Falls is a town in the province of Matabeleland North, Zimbabwe. It lies on the southern bank of the Zambezi River at the western end of the Victoria Falls themselves. It is connected by road and railway to Hwange (109 km away) and Bulawayo (440 km away), both to the south-east.

Mitchell Falls are a chain of four waterfalls located in the remote north of the Kimberley Region (Western Australia, a little more than 2,000 kilometers northeast of Perth.). It is a part of Mitchell River National Park (one of the protected areas of Western Australia), Mitchell Falls are probably one of the park’s main attractions.

Photographer Martin Schoeller examines the visual nuances of twins. Schoeller was born in Munich, Germany in 1968, studied photography at Lette Verein in Berlin and lives in New York. (Photo by Martin Schoeller)