Third place: the rear leg, claw and respiratory trachea of a louse (Haematopinus suis). (Photo by Frank Reiser/Nassau Community College/Nikon Small World Photomicrography 2021)

A hiker admires the view as Mt. Etna, Europe's largest active volcano, erupts in the background, in the Bove Valley of Etna Park, on the eastern slope of Mt. Etna, in Sicily, southern Italy, Sunday, July 4, 2021. Since Feb. 16, 2021, Mt. Etna has begun a series of eruptive episodes. (Photo by Salvatore Allegra/AP Photo)

A Bengal tigress who gave birth to four cubs at the Guadalajara Zoo, Jalisco state, Mexico runs at the zoo on October 5, 2021. (Photo by Ulises Ruiz/AFP Photo)

A man walks in the street at the start of the new curfew to counter the COVID-19 in the center of Lyon, central France, Saturday, January 16, 2021. All of France will be under a stricter curfew starting Saturday at 6 p.m. for at least 15 days to fight the spread of the coronavirus. (Photo by Laurent Cipriani/AP Photo)

Belgium's Elise Mertens, left, and Aryna Sabalenka of Belarus celebrate with their trophy after defeating Barbora Krejcikova and Katerina Siniakova of the Czech Republic in the women's doubles final at the Australian Open tennis championship in Melbourne, Australia, Friday, February 19, 2021. (Photo by Hamish Blair/AP Photo)

People wait for Pope Francis to celebrate mass at the Franso Hariri Stadium in Irbil, Kurdistan Region of Iraq, Sunday, March 7, 2021. The Vatican and the pope have frequently insisted on the need to preserve Iraq's ancient Christian communities and create the security, economic and social conditions for those who have left to return (Photo by Andrew Medichini/AP Photo)

A demonstrator smashes a shop window during a protest condemning the arrest of rap singer Pablo Hasél in Barcelona, Spain, Saturday, February 20, 2021. A fifth night of peaceful protests to denounce the imprisonment of a Spanish rap artist once more devolved into clashes between police and fringe group members who set up street barricades and smashed storefront windows in Barcelona. (Photo by Joan Mateu/AP Photo)

A Chicago Police Officer runs toward gunfire as looters break into downtown stores in the early hours of the morning on August 10, 2020. (Photo by RMV/Rex Features/Shutterstock)