Challenger Bulgarian heavyweight boxer Kubrat Pulev (R) lies in the ring after being knocked down by Ukrainian WBA, WBO, IBO and IBF heavyweight boxing world champion Vladimir Klitschko (L), who celebrates with his brother Vitali (2nd L), as referee Tony Weeks checks on him after their title fight in Hamburg, November 15, 2014. World heavyweight champion Vladimir Klitschko knocked out Bulgarian challenger Kubrat Pulev with a fierce left hook in the fifth round on Saturday to retain his IBF title and end his opponent's unbeaten record. (Photo by Fabian Bimmer/Reuters)

A new monorail service in Houston, Texas, ready for its inaugural service. (Photo by Evans/Three Lions/Getty Images). Circa 1950

Seth Casteel is an award-winning photographer and the New York Times Best Selling Author of Underwater Dogs. His new book, Underwater Puppies, was published September 16, 2014. Photo: “Underwater Puppies”: Popcicle. (Photo by Seth Casteel)

A British woman plays a piano designed especially for people who are confined to bed. Date: 1935. (Photo by Mary Evans Picture Library/Caters News)

Yaroslav Segeda at the top of a high rise building in Kudrinskaya Square, Moscow, Russia. (Photo by Yaroslav Segeda/Caters News)

Opossums on their mothers back at a game reserve in Central Minnesota, USA, on September 2, 2013. (Photo by Caters News Agency)