An unknown number of guns are being built with the mechanisms, causing problems for the police and ATF officials. Photo: An ATF agent holds a generic unfinished receiver, back, and one that has been manufactured, front, at an ATF field office in Washington, on May 06, 2014. The ATF is trying to crack down on the trade in the makeshift guns by targeting shops and individuals who offer to turn the unfinished receivers into functional pieces for firearms. (Photo by Bill O'Leary/The Washington Post)

“The Dragon and The Hopper”. Eyrean earless dragon (Tympanocryptis tetraporophora) standing tall on a very hot rock in western Queensland. For a short time it was joined by a hopper, who jumped off before becoming lunch. (Photo by Harrison Warne/Nature Conservancy Australia 2021 Photo Contest)

Retired builder Vasili Sidamonidze, 70, poses for a portrait at his home in Gori, Georgia, December 6, 2016. “Unfortunately, Stalin is not popular nowadays. Our people don't respect him. Only we, members of the (Communist) Party, respect him”, Sidamonidze said. “I always try to attend Stalin's birthday anniversaries in Gori. Unfortunately many people don't want to join us even if they live nearby. They look at us from their windows”. (Photo by David Mdzinarishvili/Reuters)

These otherworldly images give a rare glimpse inside caves barely ever seen by the human eye. With its peculiar pools of water and strange colored sediments, the bizarre looking tunnels of the Shakuranskaya cave could be a set straight out of a science fiction film. Found in the disputed region of Abkhazia, around 75 miles outside of Sochi, Russia, it is rumored the incredible underground chambers were formed after a huge earthquake struck the area in 1892. After causing part of a nearby mountain to collapse into the Amtkel River, it is thought the dam-like affect has created a series of interconnecting underground tunnels. Here: a large pool of water inside one of the tunnels. (Photo by Vladimir Mulde/Caters News)

This photographer has made it her mission to change people’s perception of pigeons – focusing on some of the most beautiful of the more than 300 species found globally. Rather than focus on the gray, nondescript birds people usually associate with the term “pigeon”, Leila Jeffreys has instead decided to snap the more vibrant varieties. Whether it be the wompoo pigeon, with its deep purple breast and green wings, or the rose-crowned fruit dove, with its pink head, Jeffreys, 46, gives the birds the same attention she would give a human model. (Photo by Leila Jefferies/Caters News Agency)

Public Space series, 2015. This series by Morteza Niknahad and Behnam Zakeri tends toward cinema, taking an almost cartoonish view of modern life in Iran. This work was inspired by the social life of dolphins. (Photo by Morteza Niknahad and Behnam Zakeri/The Guardian)

A 10-year-old pet goldfish named George undergoes veterinarian Tristan Rich's scalpel to remove a life-threatening head tumor in this handout picture taken September 11, 2014 and provided to Reuters by the Lort Smith Animal Hospital in Melbourne, Australia. In a 45-minute long procedure described by Rich as “fiddly”, the fish was sedated by water laced with anaesthetic, the tumour removed and the wound sealed with tissue glue followed by antibiotics and painkillers. (Photo by Reuters/Lort Smith Animal Hospital)

“I was on Durga Puja Festival vacation, travelling on a local train. A boy was singing devotional song and begging for alms. He was guised as a Hindu god, Lord Shiva. This is a common view in Indian trains but this boy was charming, bright and did have a melodious voice. My camera was ready hanging on my neck so I took a picture”. (Photo and caption by Arup Ghosh/2014 Sony World Photography Awards)