Supporters of the presidential candidate Muhammadu Buhari and his All Progressive Congress hits another supporter with a motorbike during celebrations in Kano, Nigeria March 31, 2015. (Photo by Goran Tomasevic/Reuters)

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)

A protester peeks out from behind of a banner as supporters of anti-immigrant activists and nationalists march to protest against the Polish governments decision to accept migrants from Syria and North Africa, in Warsaw, Poland, September12, 2015. EU President Donald Tusk said he would call a special summit on the migration crisis if the bloc's interior ministers do not display “solidarity and unity” at emergency talks on 14 September about the thousands of migrants streaming into Europe. (Photo by Jacek Turczyk/EPA)

Fighters of the Popular Resistance Committees stand during a graduation ceremony of the affiliate special forces of the Popular Resistance, in Yemen's southwestern city of Taiz October 8, 2015. (Photo by Reuters/Stringer)

Residents wade through flood waters from Tropical Storm Harvey in Beaumont Place, Houston, Texas on August 28, 2017. Houston was still largely paralyzed Monday, and there was no relief in sight from the storm that spun into Texas as a Category 4 hurricane, then parked itself over the Gulf Coast. (Photo by Jonathan Bachman/Reuters)

Cao Ri and Xu Jiaqian have a wedding photograph taken in a pool at the Qianyishi Underwater Photography Studio in Beijing, China on September 7, 2017. (Photo by Thomas Peter/Reuters)

A model presents a creation by British designer Vivienne Westwood as part of her Spring/Summer 2018 women's ready-to-wear collection show during Fashion Week in Paris, France September 30, 2017. (Photo by Charles Platiau/Reuters)

North Korean cheerleaders arrive at a rest stop, or service station, as their bus convoy carrying a 280- member delegation on its way to the 2018 Pyeongchang winter Olympic games, makes its way past Gapyeong on February 7, 2018 More than 200 young North Korean women arrived in South Korea to root for athletes from both sides of the peninsula at the Winter Olympics. (Photo by Ed Jones/AFP Photo)