In this photo taken Tuesday, October 14, 2014, skulls and bones are stacked at the Catacombs in Paris, France. The subterranean tunnels, stretching 2 kilometers (1.24 miles), cradle the bones of some 6 million Parisians from centuries past and once gave refuge to smugglers. The site used to close at 5 p.m., but is now staying open until 8 p.m. The change is mainly aimed at allowing more people to visit and reducing long lines, since it can only hold a limited number of people at a time and visits can't be reserved in advance. (Photo by Francois Mori/AP Photo)

People look on as water from the rising Mississippi River is released through the Bonnet Carre Spillway while washing out a road May 9, 2011 in Norco, Louisiana. The Army Corps of Engineers began redirecting part of the Mississippi River through the spillway today to lower river levels and reduce pressure on levees in order to avoid a catastrophic failure. The water will flow nearly 6 miles north before emptying into Lake Pontchartrain as the Mississippi rises close to the highest level ever upriver in Memphis. (Photo by Mario Tama/Getty Images)

Adam Ghiggio from Australia poses next to mutant mannequins which are lined up to be used as displays for the new video game “Rage” at the Los Angeles Convention Center on June 5, 2011 in Los Angeles, California. The Electronic Entertainment Expo officially starts on Tuesday. (Photo by Kevork Djansezian/Getty Images)

A man gestures to a robot at a restaurant in Hefei, Anhui province, December 26, 2014. The restaurant, with a space of 1300 square metres and a total of 30 robots to cook meals, deliver dishes and welcome costumers, was reported to be the biggest robot restaurant in China. (Photo by Reuters/Stringer)

Ali Carter of England looks on during the match against Stuart Bingham of England during the 2011 China Open at Beijing University Students Gymnasium on March 30, 2011 in Beijing, China.

Chinese artists perform on stage during the opening ceremony of the International Horticultural Exposition 2011 at the Exposition Park on April 28, 2011 in Xi'an, Shaanxi Province of China. The World Horticultural Exposition 2011 will be held in Xi'an from April 28 to October 22. (Photo by ChinaFotoPress/Getty Images)

Marcos Trujillo cleans the engines of a boat made by Contender in preparation for tomorrow's opening day of the four day long Progressive Insurance Miami International Boat Show at the Miami Beach Convention Center on February 15, 2012 in Miami Beach, Florida. The boat show features more than 3,000 boats and 2,000 exhibitors from all over the globe. (Photo by Joe Raedle/Getty Images)

A member of staff prepares herself a crisp sandwich in the Simply Crispy sandwich cafe in Belfast, northern Ireland January 12, 2015. The sandwich shop which opened on Monday is the world's first crisp sandwich cafe, local media reported. The idea of a crisp sandwich cafe started as a joke article on a website called Ulster Fry. The hilarious piece poked fun at recent ridiculous foody trends like the cereal café that opened in London last year. What was once a satirical joke has now become reality, after Belfast cafe owner Andrew McMenamin decided to make it happen. Customers will be able to choose their bread and crisps and add cheese or ham to their sandwich, which will be served with soup and chips. (Photo by Cathal McNaughton/Reuters)