Students of the General Yermolov Cadet School wait to board an airplane for a parachute jump at an airdrome in the village of Novomaryevskaya outside the southern city of Stavropol, Russia, May 13, 2016. (Photo by Eduard Korniyenko/Reuters)

A general view shows smoke and volcanic ashes billowing from volcano Cotopaxi in Pedregal, Ecuador, late 07 October 2015. (Photo by Jose Jacome/EPA)

A grave cleaner holds up a skull during exhumation works at the Cemetery General in Guatemala City May 24, 2013. If a lease on a grave has expired or not been paid, grave cleaners will break open the crypts to remove and rebury the bodies. (Photo by Jorge Dan Lopez/Reuters)

General Atmosphere at 2014 New York Comic Con – Day 3 at Jacob Javitz Center on October 11, 2014 in New York City. (Photo by Laura Cavanaugh/Getty Images)

A general view of Stonehenge during the annual Perseid meteor shower in the night sky in Salisbury Plain, southern England August 13, 2013. The Perseid meteor shower is sparked every August when the Earth passes through a stream of space debris left by comet Swift-Tuttle. Picture taken using a long exposure. (Photo by Kieran Doherty/Reuters)

Members of the general public enjoy the “BEACH” at the National Building Museum August 25, 2015 in Washington, DC. The “BEACH” is an interactive architectural installation, with an “ocean” of nearly one million recyclable translucent plastic balls, that brings the experience of going to the beach indoor. (Photo by Alex Wong/Getty Images)

Lali carries balloons to sell on a beach in Mumbai, India, Sunday, October 11, 2015. The United Nations General Assembly marks October 11 as the International Day of the Girl Child, to recognize girls’ rights and the unique challenges girls face around the world. (Photo by Rafiq Maqbool/AP Photo)

Skulls placed on the floor are seen during a ceremony held for the "Dia de las natitas" (Day of the Skull) celebrations at the General Cemetery of La Paz, November 8, 2015. Bolivians, who keep close relatives skulls at home as a macabre talisman, flock to the cemetery chapel once a year to have the craniums blessed and to bring themselves good luck in the future. (Photo by David Mercado/Reuters)