A prototype battery-powered plane, called Greased Lightning or GL-10 is pictured flying at NASA's Langley Research Center in this undated handout photo obtained by Reuters May 1, 2015. The plane, which has 10 engines and can take off like a helicopter and fly efficiently like an aircraft, is currently in the design and testing phase. (Photo by Reuters/NASA)

Romanian soldiers take part in a joint military exercise with NATO members, called “Agile Spirit 2015” at the Vaziani military base outside Tbilisi, Georgia, July 21, 2015. Georgian soldiers along with U.S. marines and platoon-size units from Bulgaria, Latvia, Lithuania and Romania are taking part in the exercises at the Vaziani military base outside Tbilisi. (Photo by David Mdzinarishvili/Reuters)

A passenger without pants waits for the subway train during “The No Pants Subway Ride” in Mexico City January 11, 2015. The event, the fifth organized in Mexico, is an annual flash mob and occurs in different cities around the world, according to its organisers. (Photo by Edgard Garrido/Reuters)

Fur hats are seen on display at the 2015 China Fur and Leather Products Fair in Beijing, January 15, 2015. Hundreds of domestic and foreign fur product companies take part in the fair which runs from January 13 to 16 at the National Convention Centre. (Photo by Jason Lee/Reuters)

Ukraine's Hanna Antonova competes during the 2015 World Pole Dance Championships held in Beijing, Sunday, April 12, 2015. (Photo by Ng Han Guan/AP Photo)

An iguana in Bali helped Julij Kopilović, age eight, from Slovenia, earn second runner-up in Amazing Animals. (Photo by Julij Kopilović/National Geographic)

National Beard and Moustache Championships 2015 Just for Men National Beard and Moustache Championships Presented by Hanes X-Temp, 2nd annual event honoring the best facial hair in America, with beardsmen from all over the world invited to compete. Categories include the Dali Moustache and the Full Beard Freestyle The World Beard and Moustache Association (WBMA) Championships have been held biennially since 1995 with the next competition due in 2017 in Kings Theatre, New York, NY, USA on November 7, 2015. (Photo by Dennis Van Tine/ABACAPress)

Sultan, a famous captive fennec that is displayed tied on a rope in front of a tourist shop, is the main attraction in the souk of Douz, a desert town in Tunisia. By the display of such a charismatic animal, tourists are often lured to buy things or pay for pictures. On inquiry, although Sultan has been caught as a pup in the wild, the owners of the shop reassure the foreigners stating that the animal is ‘domestic’. (Photo by Bruno D’Amicis/Fritz Pölking Prize/GDT EWPY 2015)