Zombie Punk stands for a photo during the International tattoo convention at Tobacco Dock in east London, Friday, September 27, 2019. (Photo by Aaron Chown/PA Wire Press Association via AP Photo)

Demonstrators clash with riot police during a protest against President Sebastian Piñera on October 21, 2019 in Santiago, Chile. President Sebastian Piñera suspended the 3.5% subway fare hike and declared the state of emergency for the first time since the return of democracy in 1990. Protests had begun on Friday and developed into looting and arson, generating chaos in Santiago, Valparaiso and a dozen other cities resulting in at least 8 dead. (Photo by Marcelo Hernandez/Getty Images)

University students wearing Guy Fawkes masks pose for a photoshoot of a graduation ceremony to support anti-government protests at the Hong Kong Polytechnic University, in Hong Kong, China on October 30, 2019. (Photo by Tyrone Siu/Reuters)

Stray dogs stand on tombs in Diamond Hill cemetery in Hong Kong, China, 04 April 2017. According to the lunar calendar, the Qingming Festival is observed on 04 April . The Qingming Festival, also known as Tomb-Sweeping Day, is marked by Chinese people by going to the cemetery to cleaning up tombs, bring flowers, and making offerings to their ancestors. (Photo by Jerome Favre/EPA)

Bella Thorne out and about, Los Angeles, USA on June 14, 2017. (Photo by Broadimage/Rex Features/Shutterstock)

A dune buggy driver trains before competing in a sand dune drag racing event on January 8, 2016, as part of the Liwa 2016 Moreeb Dune Festival in the Liwa desert, some 250 kilometres southwest of Abu Dhabi. The festival, which attracts participants from around the Gulf region, includes a variety of races (cars, bikes, falcons, camels and horses) or other activities aimed at promoting the country's folklore. (Photo by Karim Sahib/AFP Photo)

A participant in wingsuit flies above Tianmen Mountain at Zhangjiajie Scenic Spot during the 4th Red Bull WWL China Grand Prix on October 16, 2015 in Zhangjiajie, Hunan Province of China. The 4th Red Bull WWL China Grand Prix will last three days from October 16-18 in Zhangjiajie. (Photo by ChinaFotoPress/Getty Images)

Brain-on-a-chip. Dazzling in green and magenta this image shows the nerve fibres (in green) produced by neural stem cells (in magenta) as they grow on a synthetic gel. Captured by a technique known as confocal microscopy, the image is part of research shedding light on how tinkering with the environment can affect the way in which nerve fibres grow. (Photo by Collin Edington and Iris Lee/Massachusetts Institute of Technology/Wellcome Images)