Recruits who earned a place in the Motivation Platoon struggle through water and muck on their way to becoming a Marine or going into some other line of work, October 7, 1971. (Photo by Eddie Adams/AP Photo)

A cook grills chicken during the Festival des Grillades, in the yard of the Culture Palace of Abidjan, September 5, 2015. The two day festival was iniated in 2008 to promote Ivorian cuisine, which revolves around grilled food. (Photo by Luc Gnago/Reuters)

Ingots of 99.99 percent pure silver are cast at the Krastsvetmet Krasnoyarsk non-ferrous metals plant in the Siberian city of Krasnoyarsk, Russia, June 5, 2015. Krastsvetmet is one of the world's largest players in the precious metals industry. REUTERS/Ilya Naymushin

Radio City Music Hall Rockettes perform after days of rehearsal and routine polished to perfection at the Radio City Music Hall in New York City on July 26, 1949. (Photo by Ivan Dmitri/Getty Images)

A girl reacts while getting a nasal swab sample at a testing and screening facility for the new coronavirus in a hospital in Karachi, Pakistan, Friday, July 17, 2020. (Photo by Fareed Khan/AP Photo)

Mystical Forest. Tracey Jennings photographed this seven-gill shark in a kelp forest just off the shore of Simon's Town near Cape Town, South Africa. You don't need to travel far from cities to visit Narnia. This 7 gill shark was photographed in a kelp forest just off the shore of Simonstown near Cape Town, South Africa. (Photo by Tracey Jennings/National Geographic Travel Photographer of the Year Contest)

A soldier stands guard on the aircraft park of the Pyongyang Airport on April 3, 2011 in Pyongyang, North Korea. Pyongyang is the capital city of North Korea and the population is about 2,500,000.

2016 Rio Olympics, Weightlifting, Final, Women's 69kg, Riocentro, Pavilion 2, Rio de Janeiro, Brazil on August 10, 2016. Leidy Solis (COL) of Colombia competes. (Photo by Stoyan Nenov/Reuters)