Sugar gliders, Candy and Popcorn, enjoy their favourite food, Nectar, at Wild Life Sydney Zoo on February 14, 2017 in Sydney, Australia. The treat made up of honey, high protein baby cereal and egg yolks is the human equivalent to chocolate to the Sugar Gliders. St. Valentine's Day or the Feast of Saint Valentine began as a celebration of the early Christian Saint Valentinus. From the 18th Century onwards it has steadily transformed into a celebration of romantic love and sentiment in many countries around the world. (Photo by James D. Morgan/Getty Images)

A student from the General Yermolov Cadet School performs with models of swords during celebrations of Maslenitsa, or Pancake Week, a pagan holiday marking the end of winter, in southern city of Stavropol, Russia, March 6, 2019. (Photo by Eduard Korniyenko/Reuters)

In this April 18, 2019 photo, tattoo artist Lalo Calva inks a tattoo on client Adrian Alonso Rodriguez, a journalist, announcer and dubbing artist, at the Corona Tattoo parlor in Mexico City. Not only inks and techniques have changed in Mexico over the years, but tattoos themselves have evolved from stigmatized symbols of gangs, violence and poverty to an art form. (Photo by Marco Ugarte/AP Photo)

Long row of shiny new Flying Fortresses, part of huge reserves being built up in Britain for D-Day, stands by to be flown to combat units as replacements, May 25, 1944. (Photo by AP Photo)

The Mayon volcano continues to erupt as the sun sets behind Legazpi city, Thursday, January 25, 2018 in Albay province, roughly 340 kilometers, (200 miles) southeast of Manila, Philippines. (Photo by Bullit Marquez/AP Photo)

A visitor takes a picture of goldfish at the Art Aquarium exhibition in Tokyo Friday, August 12, 2016. The exhibition, featuring around 8,000 goldfish in tanks themed on Japan's Edo Period. (Photo by Koji Sasahara/AP Photo)

People wearing costumes walk during Halloween in Sierra Madre, California, U.S., October 31, 2017. (Photo by Mario Anzuoni/Reuters)

People make their way on an algae-covered beach in Qingdao, Shandong province, China, July 19, 2015. (Photo by Reuters/Stringer)