Most pet cats will become timid or defensive when outdoors, but not Millie – after being adopted by her mountain-climbing owner Craig Armstrong, Millie has become a feline hiking and mountain-climbing legend.

Australian photographer Brendan Fitzpatrick’s X-ray photographs expose the inner workings of toys. Fitzpatrick’s photographs are both whimsical and mechanical, evoking the curiosity of childhood and the desire to discover how things look and work from other perspectives. The strategic placement of wires, batteries, and screws are revealed, the complexity of the inside contrasting with the seemingly simplistic design of the outside. Fitzpatrick uses chest X-ray and mammogram machines to photograph flowers, toys, and creatures, then enhances the color in the images in order to more effectively distinguish the various parts that have been exposed. This photographs are part of series he calls “Invisible Light”. (Photo by Brendan Fitzpatrick)

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)

Rescued Dutch hikers exit a search and rescue snowcat after they were brought safely to Grotli, Norway, February 26, 2016. Thirteen Dutchmen who were stranded while hiking in central Norway's mountains were found after snowmobile patrols by the Red Cross. Snowcats from the Red Cross are now moving ahead to pick the hikers up. (Photo by Torstein Boe/Reuters/NTB Scanpix)

The sun rises between Sgurr nan Gillean and Knight’s Peak, Black Cuillin, Isle of Skye. (Photo by Adrian Trendall/Mountain Photo of the Year)

A dog is kept at a pen at the newly opened Central Zoo in Pyongyang, North Korea, Tuesday, August 23, 2016. One of the most popular attractions at the zoo might come as a surprise to foreign visitors. Just across the way from the hippopotamus pen and the reptile house, dozens of varieties of dogs, including schnauzers, German shepherds, Shih Tzus and Saint Bernards – are on display in the “dog pavilion”. (Photo by Dita Alangkara/AP Photo)

Two fourteen-week old lion cubs, a male named Ramzes and a female named Zara, are seen during a Christening ceremony at the Bojnice Zoo April 4, 2015. The two cubs are Barbary lions (Panthera leo leo), local media reported. (Photo by Radovan Stoklasa/Reuters)

“These photographs show the food chain in action as a hungry lion braved a river full of crocodiles to try and sink his teeth into a dead hippo. The photos were taken in the Maasi Mara nature reserve, in Kenya and show hungry lion braving a crocodile-infested river to get to an upside down hippo, which had died overnight of natural causes”. – Caters News. (Photo by Richard Chew/Caters News)