In Omdurman, the largest city in Sudan, the Qadiriyya Sufi order meets every Friday outside Sheikh Hamed Al Nil mosque, which houses the tomb of their 19th century Sufi leader. (Photo by Ala Kheir, John Burns and Ibrahim Algrefwi/Brownbook)

A volcanic eruption at Mount Etna’s Vorgaine crater in Sicily, Italy on December 3, 2015. (Photo by Marco Restivo/Barcroft Media)

In this Tuesday, March 10, 2015 photo, rime ice covers rocks on the summit of Mount Washington in New Hampshire. Rime ice occurs when freezing fog hits stationary objects in frigid conditions. (Photo by Robert F. Bukaty/AP Photo)

A tired-looking Javan Fish Owl. (Photo by Fox Photos/Getty Images). 5th December 1973

“Romantic”. A brown bear in Martinselkonen, Finland. (Photo by Valtteri Mulkahainen/Comedy Wildlife Photography Awards)

This absolute hero came to the rescue when flash floods in a World Cup city left two women stranded in their submerged cars. Here: A woman is rescued from a car after a flash flood in Nizhny Novgorod, Russia on June 19, 2018. (Photo by Lucy Nicholson/Reuters)

Contestants of a tattoo competition pose for photographs at the China TATTOO convention in Nanning, Guangxi Zhuang Autonomous Region, China, October 24, 2015. The annual convention was held in Nanning from October 23 to 25 this year. (Photo by Reuters/Stringer)

A boy crawls under a cow during a religious ceremony celebrating the Tihar festival, also called Diwali, in Kathmandu, October 23, 2014. Hindus all over Nepal are celebrating the festival during which they worship cows, which are considered a maternal figure, and other animals. Also known as the festival of lights, devotees worship the goddess of wealth Laxmi by illuminating and decorating their homes using garlands, oil lamps, candles and colourful light bulbs. (Photo by Navesh Chitrakar/Reuters)