Mask dancers take part in a parade during the the International Festival of Masquerade Games “Surva” in the town of Pernik, some 30 km from Sofia, Bulgaria, January 31, 2016. (Photo by Vassil Donev/EPA)

A model presents a creation by Chinese designer Hu Sheguang from Sheguang Hu collection at China Fashion Week in Beijing, March 31, 2016. (Photo by Jason Lee/Reuters)

Visitors walk through a tulip display in Chaya Mountain, Suiping County in Zhumadian, Henan Province of China on March 31, 2016. There are more than ten varieties of tulips here. (Photo by VCG/VCG via Getty Images)

A fighter of Libyan forces allied with the U.N.-backed government runs for cover during a battle with Islamic State fighters in Sirte, Libya, July 31, 2016. (Photo by Goran Tomasevic/Reuters)

Riot police fire tear gas during a protest by supporters of Dilma Rousseff in Sao Paulo, Brazil August 31, 2016. (Photo by Paulo Whitaker/Reuters)

Members of the Beltane Fire Society take part in Samhuinn Fire Festival on October 31, 2023 in Edinburgh, Scotland. Once celebrated from October 31 to November 1 by ancient Celts, Samhain, pronounced “SOW-in” or “SAH-win”, marked the shift from the brighter to the darker half of the year and was seen as a time when the boundary between the physical and spirit worlds was thought to weaken, influencing the development of contemporary Halloween customs. (Photo by Murdo MacLeod/The Guardian)

David Nicholson, 21, surfs as "The Mask" during the ZJ Boarding House Haunted Heats Halloween Surf Contest in Santa Monica, California, United States, October 31, 2015. (Photo by Lucy Nicholson/Reuters)