Coloured X-ray of a barn owl. A physicist has used X-ray to create an extraordinary collection of artwork. Arie van't Riets pictures reveal birds, fish, monkeys and flowers in an incredible new light. The 66-year-old, from Bathmen in the Netherlands, began X-raying flowers as a means to teach radiographers and physicians how the machine worked. But after adding a bit of colour to the pictures, the retired medical physicist realised the potential for an exciting new collection of art. (Photo by Arie van't Riet/Barcroft Media)

Fish are thrown onto a truck during a winter fishing festival held on the frozen Wulungu Lake in Fuhai county, Xinjiang Uighur Autonomous Region, January 18, 2015. (Photo by Reuters/China Daily)

Andy Goldfarb, a staff biologist at the Point Defiance Zoo & Aquarium, plays with one of the four clouded leopard cubs currently at the zoo Friday, June 5, 2015 in Tacoma, Wash. The quadruplets were born on May 12, 2015 and now weigh about 1.7 lbs. each. Friday was their first official day on display for public viewing, usually during their every-four-hours bottle-feeding sessions, which were started after the cubs' mother did not show enough interest in continuing to nurse them. (AP Photo/Ted S. Warren)

An Afghan man works at a traditional yarn factory in Heart province, Afghanistan July 28, 2015. (Photo by Mohammad Shoib/Reuters)

A Nepalese boy gets ready to perform a stick dance during a rally held to pay tribute to the victims of an earthquake, in Bhaktapur, Nepal, Wednesday, September 2, 2015. Two powerful earthquakes in April and May devastated the Himalayan nation killing more than 8,800 people. (Photo by Niranjan Shrestha/AP Photo)

A model presents a creation during the Biofashion show, which features designs made from plants, recycled and natural materials, in Cali, Colombia, November 19, 2016. BioFashion is an environmental initiative that seeks to create awareness about the preservation and management of natural resources where new designers develop dresses made with living plants, flowers and organic elements. (Photo by Jaime Saldarriaga/Reuters)

In this July 20, 2019 photo, children play during a sports event organized by members of the Caracas FC soccer club, in Catia, one of the poorest slums in Caracas, Venezuela. When the Caracas Football Club plays, its supporters leave their ideological preferences and socioeconomic differences behind, joining together to support and take care of each other inside and outside the stadium. (Photo by Matias Delacroix/AP Photo)

Yeshiva School students briefly dance on Grant Street after the menorah lighting outside of the City-County Building for the fifth night of Hanukkah, Thursday, December 26, 2019, in downtown Pittsburgh. (Photo by Alexandra Wimley/Pittsburgh Post-Gazette via AP Photo)