Students wearing mask hold hands to surround the St. Stephen's Girls' College in Hong Kong, Monday, September 9, 2019. Thousands of demonstrators in Hong Kong urged President Donald Trump to “liberate” the semiautonomous Chinese territory during a peaceful march to the U.S. Consulate on Sunday, but violence broke out later in the business and retail district as police fired tear gas after protesters vandalized subway stations, set fires and blocked traffic. (Photo by Kin Cheung/AP Photo)

The photographs feature fish that have been specially treated to make the stained skeletal tissues visible through the skin and flesh. The technique, developed by Dr. Adam Summers, uses dyes, hydrogen peroxide, a digestive enzyme and glycerin to make the flesh seem to disappear. Photo: This image of the butterfly ray (Gymnura crebripunctata) helped scientists study the joints in its wings. (Photo by Adam Summers)

A Cavalier King Charles Spaniel competes in the Masters Agility Championship Finals competition during the 141st Westminster Kennel Club Dog Show in New York City, U.S. February 11, 2017. (Photo by Brendan McDermid/Reuters)

Border Security Force (BSF) “Daredevils” women motorcycle riders perform during a rehearsal for the Republic Day parade on a cold winter morning in New Delhi, January 10, 2018. (Photo by Adnan Abidi/Reuters)

School children take shelter under desks during a tsunami simulation drill ahead of World Tsunami Awareness Day at Futaba elementary school in Choshi, Chiba Prefecture, Japan, November 4, 2016. (Photo by Kim Kyung-Hoon/Reuters)

Catholic faithfuls hold figurines of baby Jesus during a religious procession on Holy Innocents Day in Antiguo Cuscatlan, El Salvador, December 28, 2016. (Photo by Jose Cabezas/Reuters)

Competitors line up their boats for some formalities during the Aberdeen Dragon Boat Races. (Photo by Jessica Hromas)

Vian Salman, center, smiles with fellow contestants after she was crowned the new Miss Iraq during the Miss Iraq contest in Baghdad, Iraq, Thursday, May 25, 2017. (Photo by Karim Kadim/AP Photo)