A large bull walrus returns to the shores of Prins Karl Forland after diving and feeding on clams. (Photo by Paul Nicklen/National Geographic). Svalbard, Norway, 2011

Turkey's Merve Aydin cries after she came in last in her women's 800m round 1 heat at the London 2012 Olympic Games at the Olympic Stadium August 8, 2012. (Photo by Lucy Nicholson/Reuters)

Hooded demonstrators vandalise a shop window in Mexico City, during the commemoration of the 50th anniversary of the 1968 Tlatelolco student massacre, on October 2, 2018. Fifty years ago, Mexican troops opened fire on student demonstrators, killing hundreds just days before Mexico City hosted the 1968 Olympics – one of the darkest episodes in a year of global turbulence. (Photo by Ronaldo Schemidt/AFP Photo)

Protesters use fireworks against riot police during clashes in the Athens neighborhood of Exarchia, a haven for extreme leftists and anarchists, Thursday, December 6, 2018. New protest marches were underway in Greece Thursday evening on the 10th anniversary of the fatal police shooting of a teenager, hours after violent initial demonstrations where masked youths attacked police with firebombs and stones. (Photo by Yorgos Karahalis/AP Photo)

A leaf from a sweetgum tree (Liquidambar styraciflua) lies on the grass at Godewaersvelde early October 27, 2017. (Photo by Philippe Huguen/AFP Photo)

A Sadhu, or a Hindu holy man, performs yoga on International Yoga Day at Kamakhya temple in Guwahati, India on June 21, 2018. (Photo by Anuwar Hazarika/Reuters)

Cars sit abandoned in a former shopping centre in the United Nations buffer zone in central Nicosia March 12, 2014. The cars were imported from Japan to be sold at a Toyota dealership. They were stored here during the 1974 conflict and have not been moved since. (Photo by Neil Hall/Reuters)