Shell, which is the replica of the biggest detonated Soviet nuclear bomb AN-602 (Tsar-Bomb), is on display in Moscow, Russia, August 31, 2015. The shell is part of an exhibition organized by the state nuclear corporation Rosatom. (Photo by Maxim Zmeyev/Reuters)

Mahouts and their elephants display a poster during a campaign ahead of the August 7 referendum in Auytthaya province, north of Bangkok, Thailand, August 1, 2016. Officials across the country are drumming up campaigns to encourage voting on the draft constitution in a referendum on Sunday. (Photo by Chaiwat Subprasom/Reuters)

“People of the River”. This is a Karo tribe family; father, mother, two sisters and two brothers. The tribe, who live along the Omo River in east Africa, incorporate rich symbolism into their rituals by using ornate body art, headdresses and body scarification to express beauty and significance. (Photo by Jatenipat Ketpradit/International Portrait Photographer of the Year)

Women, wearing traditional “ao dai” dress, pose for a photo next to peach blossom flowers ahead of Vietnamese “Tet” (the lunar new year festival) in a field in Hanoi January 22, 2017. (Photo by Reuters/Kham)

A young boy rests by empty USAID vegetable oil tins in the Dagahaley refugee camp which makes up part of the giant Dadaab refugee settlement on July 19, 2011 in Dadaab, Kenya. The refugee camp at Dadaab, located close to the Kenyan border with Somalia, was originally designed in the early 1990s to accommodate 90,000 people but the UN estimates over 4 times as many reside there. The ongoing civil war in Somalia and the worst drought to affect the Horn of Africa in six decades has resulted in an estimated 12 million people whose lives are threatened. (Photo by Oli Scarff/Getty Images)

Recreation time for the seminarists at St. Ignatius Loyala shrine at Azpeitia, Gipuzkoa (Guipúzcoa) in Spain. (Photo by Evans/Getty Images). 1955

Ukrainian teenagers hit each other with pillows during a large pillow fight in downtown Kiev, Ukraine, 24 April 2016. About hundred people took part in the event “Pillow battle 2016” in Kiev. (Photo by Roman Pilipey/EPA)

Gurung girls wearing traditional costumes dance while taking part in a New Year parade in Kathmandu, Nepal December 30, 2015. Members of the Gurung community in Nepal celebrate their Tamu Lhosar or Losar (New Year) with a feast and various cultural programs to usher in the year of the Monkey. (Photo by Navesh Chitrakar/Reuters)