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)

Girls rest on stairs at the China Digital Entertainment Expo and Conference (ChinaJoy) in Shanghai, China July 27, 2017. (Photo by Aly Song/Reuters)

Young revelers take part in a parade called "La Calabiuza" on November 1, 2015, on the eve of the Day of the Dead in Tonacatepeque, 20 kms (13 miles) north of San Salvador. During the celebration, the residents of Tonacatepeque, originally an indigenous community, recall the characters from the mythology of Cuscatlan – pre-Columbian west and central regions of El Salvador – and their dead relatives. (Photo by Marvin Recinos/AFP Photo)

A worker loads palm fruit at a palm oil plantation in North Mamuju regency, West Sulawesi province, Indonesia March 10, 2016 in this photo taken by Antara Foto. (Photo by Sahrul Manda Tikupadang/Reuters/Antara Foto)

In this 1997 photo released by the International Fund for Animal Welfare, a seal hunter, right, threatens a cameraman with a knife during the filming of a seal hunt in the Gulf of St. Lawrence, Canada. “Huntwatch”, a documentary by the organization about the fight to end commercial seal hunts, premieres in September 2016 on Discovery. The producers say it includes grainy but powerful archive footage that had languished in the basement of the group’s headquarters on Cape Cod for nearly five decades. (Photo by Richard Sobol/IFAW via AP Photo)

Police detain demonstrators during an action against Russia's attack on Ukraine in St. Petersburg, Russia, Monday, February 28, 2022. Protests against the Russian invasion of Ukraine resumed on Monday, with people taking to the streets of Moscow and St. Petersburg and other Russian towns despite mass arrests. (Photo by Dmitri Lovetsky/AP Photo)

A zoo performer smiles as he puts his head between the jaws of a crocodile during a performance for tourists at the Sriracha Tiger Zoo, in Chonburi province, east of Bangkok,Thailand, June 7, 2016. (Photo by Chaiwat Subprasom/Reuters)

A Hindu devotee ululates as she holds a banana tree trunk after taking a dip in the waters of the Ganges river during a ritual as part of the Durga Puja festival in Kolkata, India, September 27, 2017. (Photo by Rupak De Chowdhuri/Reuters)