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)

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)

Family members mourn the passing of Manuela Chavez, who died from symptoms related to the new coronavirus at the age of 88, as a government team prepares to remove her body from inside her home, in the Shipibo Indigenous community of Pucallpa, in Peru's Ucayali region, Monday, August 31, 2020. While the lucky are cured with ancestral ailments, the less fortunate often die at home. A government team travels from one spartan, thatch-roofed home to the next, removing the dead from their homes where they took their last breaths. (Photo by Rodrigo Abd/AP Photo)

A taxi driver seen sleeping on his taxi in the middle of a decorated street during the Durga Puja Festival in Kolkata, India on October 22, 2020. (Photo by Avishek Das/SOPA Images/Rex Features/Shutterstock)

Passengers wears a face mask while riding on a bus after new cases of COVID-19 were reported in Peshawar, Pakistan, 18 November 2020. Countries around the world are taking increased measures to stem the widespread of the Covid-19 disease. (Photo by Arshad Arbab/EPA/EFE/Rex Features/Shutterstock)

Young women pose for photos in a Christmas-themed tunnel lit-up with decorations outside a shopping mall in Bangkok on December 4, 2020. (Photo by Mladen Antonov/AFP Photo)