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)

Two Inuit children at Point Barrow, Alaska, holding the tusks of a large walrus, probably killed for food, circa 1930. (Photo by General Photographic Agency/Getty Images)

Pope Francis attends a circus performance during his weekly general audience at Paul VI hall on December 22, 2016 at the Vatican. (Photo by Alberto Pizzoli/AFP Photo)

General view of a herbal store in Cairo, Egypt January 10, 2017. In an economic crisis that has led to a shortage of medicines, Egyptians are skipping trips to drug stores and instead turning to herbal remedies to treat every-day illnesses. (Photo by Mohamed Abd El Ghany/Reuters)

A member of staff stands in front of a CRH high-speed train at Shanghai Hongqiao Railway Station during its test run on May 11, 2011 in Shanghai, China. After 3 years construction, from April in 2008, with total investment estimated at 220.9 billion yuan (around 32.5 billion U.S. dollars), the Beijing-Shanghai high-speed railway begins a one-month trial operation. It is expected to start operation in June this year, with the travel time between the two cities reducing to five hours from the previous 10. (Photo by ChinaFotoPress/Getty Images)

A racehorse is hoisted up before its operation at Veliefendi equine hospital in Istanbul March 3, 2015. A state-of-the-art hospital for hundreds of horses run by the Jockey Club of Turkey at Istanbul's Veliefendi racecourse is the country's oldest and biggest. Grooms and trainers at the equine clinic work with vets and nurses while owners hope their prize runners, often worth hundreds of thousands of dollars, will recover quickly and then run faster still. (Photo by Murad Sezer/Reuters)