A tour group wanders through block 7 of Eastern State Penitentiary in Philadelphia, Pennsylvania April 30, 2014. Opened in 1829, with the original corrective system of “confinement in solitude with labor”, the penitentiary housed about 75,000 inmates in its 142 years of operation. At Eastern State reunions, former inmates, staff and guard gather to share memories and trade stories and get a chance to describe their experiences in question-and-answer sessions with the public. (Photo by Mark Makela/Reuters)

Employees of a food stand take pictures of Titan, a robot created by England Cyberstein Robots, performing at the Danilovsly market in downtown of Moscow, Russia, 12 May 2014. Titan visited to Moscow to attend “Bal Robotov”, an interactive exhibition of the most recent advances in robotics which will be opened on 15 May in Artplay Moscow exhibition center. Titan worked alongside superstars including Will.i.am, Rihanna, Will Smith and Jackie Chan. (Photo by Sergei Ilnitsky/EPA)

These unique photos capture the moment a boy has his teeth picked clean by amazing underwater shrimp. These fascinating creatures spend their lives diving inside the mouths of fish to remove the parasites that lurk there. Russell Laman imitated the behaviour of the surrounding fish swarm to entice the cleaner shrimp into his mouth whilst snorkelling with his father Tim Laman in Bali, Indonesia. The 13-year-old queued with the waiting fish and then opened his mouth when the shrimps came near. (Photo by Tim Laman/Caters News)

Take a look at this stunning photo of Tolbachik, an active volcanic complex on the Kamchatka Peninsula in far eastern Russia. Lava fountains and rivers ran through the area for months after the eruption began with the opening of two Tolbachik fissures in November of 2012. In the midst of this activity, photographers Luda and Andrey (lusika33) took a trip down to see that stunning hell valley on earth. (Photo by lusika33)

A portrait of late communist leader Mao Zedong is seen behind two hostesses as they pose for a picture at the Tiananmen Square during the 3nd plenary session of the National People's Congress in Beijing on March 13, 2016. China's Communist-controlled parliament opened its annual session on March 5 and is expected to appove a new five-year plan to tackle slowing growth in the world's second-largest economy. (Photo by Wang Zhao/AFP Photo)

A Thai visitor appears to be frightened by a life-size Velociraptor model also known as Raptor at the Dinosaur Planet theme park in Bangkok, Thailand, 25 March 2016. The 500 million baht (14 million US dollars or 12 million euro) theme park opening in the Thai capital aimed to attract more than 15,000 visitors a day featuring a chance to experience more than 200 dinosaurs from various species that are brought back to life. (Photo by Rungroj Yongrit/EPA)

In this April 2, 2016 photo, dusty sculptures made of cast-off baby dolls sit in an open-air museum and art workshop off a trash-strewn street cutting through some of the poorest neighborhoods in Port-au-Prince, Haiti. They were created by Haitian artists called Atis Rezistans who have become celebrated in the international art world by creating sculptures out of scrapped car parts, old wood, discarded toys and even human skulls found scattered outside crumbling mausoleums. (Photo by David McFadden/AP Photo)

A reveler and a child street vendor pose for a photo during the Banda de Ipanema Carnival parade in Rio de Janeiro, Brazil, Saturday, January 31, 2015. Rio's over-the-top Carnival is the highlight of the year for many local residents. Hundreds of thousands of merrymakers are beginning to take to the streets in open-air “blocos” parties. (Photo by Silvia Izquierdo/AP Photo)