A mudlark uses a torch to look for items on the bank of the River Thames in London, Britain June 06, 2016. Mudlarking is believed to trace its origins to the 18th and 19th century, when scavengers searched the Thames' shores for items to sell. These days, history and archaeology fans are the ones hoping to find old relics such as coins, ceramics, artifacts or everyday items from across centuries. their finds with the Portable Antiquities Scheme. Any item over 300 years old must be recorded. (Photo by Neil Hall/Reuters)

Children wearing uniforms hold toy guns during a military parade game on China's National Day, at Beyou World, a centre children where can experience different kinds of professions, in Beijing, October 1, 2015. (Photo by Reuters/Stringer)

Singer Rihanna in the audience at the 54th Annual GRAMMY Awards held at Staples Center on February 12, 2012 in Los Angeles, California. (Photo by Larry Busacca/Getty Images For The Recording Academy)

A woman touches a robot at the 2018 World Robot Conference in Beijing on August 15, 2018. The conference will be held from 15 to 19 August and will include a conference on robotics, an exhibition and a robot competition with the participation of robotics enterprises to showcase their robot products. (Photo by Wang Zhao/AFP Photo)

North Korean soldiers wave along the Yalu River, near the North Korean town of Sinuiju, opposite to the Chinese border city of Dandong October 7, 2014. (Photo by Jacky Chen/Reuters)

A glass skywalk in Wanyuan, Sichuan province, built along the side of a cliff, is the highest such skywalk anywhere in China on January 31, 2017. Some visitors have been proven to be terrified by the experience had to brace against the wall in fear. (Photo by Chinanew.com/AsiaWire)

A giant Iron Man statue stands next to a replica Sphinx in Chuzhou, Anhui Province, China on February 21, 2017. (Photo by Sipa Asia/Rex Features/Shutterstock)

The pit lane is reflected in the visor of a Mercedes Formula One pit crew member during the second practice session of the Australian F1 Grand Prix at the Albert Park circuit in Melbourne March 13, 2015. REUTERS/Brandon Malone