A man smashes an apple with a sword placed on the head of a man wearing a knave costume during the Easter knight event on April 21, 2014 in Berlin. The easter knight event delivers an insight into medieval lifestyle. (Photo by Rainer Jensen/AFP Photo/DPA)

“The Challenge!” Young boy relishes in a game of tug of war before school. Photo location: Lake Titicaca, Peru. (Photo and caption by Paul Heyman/National Geographic Photo Contest)

Ghanaian fans take a selfie prior to a Group G football match between Germany and Ghana at the Castelao Stadium in Fortaleza during the 2014 FIFA World Cup on June 21, 2014. (Photo by Patrik Stollarz/AFP Photo)

Large trumpet vines spread across electrical lines next to a highway in Kinston, N.C., on June 23, 2014. (Photo by Janet S. Carter/Kinston Free Press via AP Photo)

Yerevan residents celebrate Armenian Prime Minister's Serzh Sargsyan's resignation in Yerevan, Armenia, Monday, April 23, 2018. Sargsyan resigned unexpectedly on Monday, an apparent move to bring to an end massive anti-government protests. (Photo by Amos Chapple/RFE/RL)

Chloe Ferry attends the Geordie Shore series 15 “Shag Pad on Tour” cast launch at Tower Bridge on August 16, 2017 in London, England. (Photo by Karwai Tang/WireImage)

A wolf-like robot “Super Monster Wolf” stands beside a rice field to drive away wild animals that cause damages to crops in Kisarazu, Chiba prefecture, on August 25, 2017. The agricultural coopetative association JA Kisarazu-shi introduced the 65cm-long and 50cm-high robot recently on a trial basis which can detect wild animals such as boars and deers with an infrared ray sensor when they approach and intimidates them, flashing the red LED eyes and blaring 48 types of sounds including a wolf growl and human voice. (Photo by Toru Yamanaka/AFP Photo)

An AH-64D Apache attack helicopter flies in front of a wall of fire during the South Carolina National Guard Air and Ground Expo at McEntire Joint National Guard Base, South Carolina, U.S. on May 6, 2017. (Photo by Jorge Intriago/Reuters/Courtesy Air National Guard)