Paramilitary policemen take part in a summer training in Shenzhen, Guangdong province, China, June 27, 2016. (Photo by Reuters/China Daily)

A U.S. Marine leads training on a shooting range in France in an undated photo taken during the First World War. (Photo by Reuters/Courtesy Library of Congress)

In a photo taken on October 7, 2020 a woman holds two dogs as she waits for a train in Suncheon. (Photo by Ed Jones/AFP Photo)

A man sleeps in a subway train in New York city on August 1, 2024. (Photo by Charly Triballeau/AFP Photo)

Urszula Sidoruk, 19, from the paramilitary group SJS Strzelec (Shooters Association), trains her workout at a gym in Siedlce, eastern Poland March 18, 2014. Inspired by the war in Ukraine, growing numbers of Poles are joining volunteer paramilitary groups, where they receive basic army training and prepare to defend their homeland. (Photo by Kacper Pempel/Reuters)

National Diving School director Jerome Vincent, wearing a Gandolfi space suit, executes training procedures in a swimming pool in Marseille October 22, 2014. The underwater test session develops European expertise in spacewalk simulations under partial gravity for exploring the Moon, asteroids and Mars.The training is organised by Comex, a French company specializing in engineering and deep sea diving operations, in collaboration with the European Space Agency (ESA) and with Apollo XI “Under the sea”. (Photo by Jean-Paul Pelissier/Reuters)

While vacationing on the Maldives Islands, Taiwanese amateur photographer Will Ho stumbled onto an incredible stretch of beach covered in millions of bioluminescent phytoplankton. These tiny organisms glow similarly to fireflies and tend to emit light when stressed, such as when waves crash or when they are otherwise agitated. While the phenomenon and its chemical mechanisms have been known for some time, biologists have only recently began to understand the reasons behind it. Photo: Bioluminescent phytoplankton washes up on Maldives beach. (Photo by Will Ho)

In this October 6, 2018, photo, a craftsman makes daggers or “Jambiyya” in Yemeni Arabic, made out of remains of missiles, at his workshop, in Hajjah, Yemen. Missiles raining on Yemen from the jets of the Saudi-led coalition fighting Houthi rebels are killing thousands of civilians and militiamen alike, but amid crashing economy, some Yemenis see the bright side of it: they make daggers out of the fragments of the missiles for ordinary men traditionally wear for prestige and a show of courage. (Photo by Hammadi Issa/AP Photo)