A worker puts the final touches to a replica of a Beijing opera mask made with lemons and oranges during the 82th Lemon festival in Menton February 12, 2015. Over 20,000 hours work for teams to set up the festival and some 145 metric tons of lemons and oranges are used to make displays during the 82th festival, which is themed “Tribulations of a lemon in China”, and runs from February 14 through March 4. (Photo by Eric Gaillard/Reuters)

Anand Varma, a U.S. photographer working for the National Geographic, won the First Prize in the Nature Category, Stories, of the 2015 World Press Photo contest with his series of pictures, which includes this one of spores of a fungus landing on an ant, penetrating its exoskeleton and entering its brain, compelling the host to leave its normal habitat on the forest floor and scale a nearby tree, in this picture taken January 22, 2014 and released by the World Press Photo on February 12, 2015. (Photo by Anand Varma/Reuters/National Geographic/World Press Photo)

Monks dressed as Tibetan Buddhism characters attend a religious ceremony, known as “Da Gui” or beating ghost, to celebrate the upcoming Tibetan New Year which starts on March 1 at Yonghegong Lama Temple, in Beijing February 28, 2014. This Tibetan ceremony is held annually at the end of the first lunar month with mask dancing to expel ghosts, according to a press release. (Photo by Jason Lee/Reuters)

Residents observe a police officer take up position during an operation at the Mare slums complex in Rio de Janeiro March 25, 2014. The federal troops have taken control of security operations in Mare slums complex to help quell a surge in violent crime following attacks by drug traffickers on police posts in three slums on the north side of the city, government officials said. (Photo by Ricardo Moraes/Reuters)

Situated 10km outside Nairobi city centre, this private giraffe sanctuary is centred around a colonial manor house named Giraffe Manor. Living within the grounds is a herd of rare Rothschild giraffe. The giraffes visit twice a day searching for food, before returning to the forest. Although still wild animals, they have become accustomed to receiving treats from residents and guests. (Photo by Klaus Thymann)

A window cleaner passes a lighter to his colleague while rappelling from a new building in Tianjin March 23, 2007. (Photo by Reuters/Stringer)

Gus Palmer (Kiowa, at left), side gunner, and Horace Poolaw (Kiowa), aerial photographer, in front of a B-17 Flying Fortress. MacDill Field, Tampa, Florida, ca. 1944. (Photo and caption by 2014 Estate of Horace Poolaw)