“Slow”. A calm cow in the messy streets of Jodhpur. Photo location: India. (Photo and caption by Matthias Troeger/National Geographic Photo Contest)

A general view of the sunrise over Hawes, Wensleydale, UK on November 24, 2014. (Photo by Neil Squires/PA Wire)

Animals destined for the stage of Radio City Music Hall in New York on November 13, 1986 are led to the stage door by their co-stars, the Rockettes dancers. A variety of animals, including camels, sheep and donkeys, will star in an annual Christmas production. (Photo by G. Paul Burnett/AP Photo)

In this February 7, 2014 file photo, Matt Figi hugs and tickles his once severely-ill seven year old daughter Charlotte, as they walk together inside a greenhouse for a special strain of medical marijuana known as Charlotte's Web, which was named after the girl early in her treatment for crippling severe epilepsy, in the mountains west of Colorado Springs, Colo. Colorado is poised to award more than $8 million for medical marijuana research, a step toward addressing complaints that little is known about pot's medical potential. Among the research projects poised for approval on Wednesday, December 17, 2014, are one for pediatric epilepsy patients, and another for children with brain tumors. (Photo by Brennan Linsley/AP Photo)

U.S. President Barack Obama laughs as he reads the storybook “Where the Wild Things Are” during the annual Easter Egg Roll at the White House in Washington April 6, 2015. Thousands of children gathered at the White House for the annual Easter Egg Roll. This year's event features live music, cooking stations, storytelling, and of course, some Easter egg roll. (Photo by Jonathan Ernst/Reuters)

A Green Crowned Brilliant is pictured at a Hummingbird feeding station on January 15, 2016 in Alajuela Costa Rica. Of the 338 known species of Hummingbird worldwide there are around 50 in Costa Rica. Hummingbirds are named for the distinctive sound made by their tiny beating wings, and are admired for their vibrantly coloured iridescent plumage. Their ability to hover, with wings beating between 12 and 90 times a second, and to fly backwards makes them different from all other birds. (Photo by Dan Kitwood/Getty Images)

A bride gets her make-up done before the start of a mass marriage ceremony in Kolkata, India, February 14, 2016. A total of 150 tribal Hindu, Muslim and Christian couples from various villages across the state took their wedding vows on Sunday during the day-long mass marriage ceremony organised by a social organisation, the organisers said. (Photo by Rupak De Chowdhuri/Reuters)

A picture taken on October 17, 2017 shows Madame Tussauds museum's wax figure of US President displayed along the East Side Gallery section of the Wall in Berlin during a photo session. The wax figure will be displayed at Madame Tussauds museum in Berlin from October 20, 2017. (Photo by Jens Kalaene/AFP Photo/DPA)