A pro-democracy protester wearing a Guy Fawkes mask holds a yellow umbrella and a banner in the part of Hong Kong's financial central district protesters are occupying November 2, 2014. The former British colony of Hong Kong, which returned to Chinese rule in 1997, has witnessed a month of protests calling on the Beijing-backed government to keep its promise of introducing universal suffrage. The protests have for the most part been peaceful, with occasional clashes between the student-led protesters and Beijing supporters seeking to move them from the streets. (Photo by Damir Sagolj/Reuters)

“Hippo Chase”. As we approached the camp the Selinda Reserve of northern Botswana our boat passed by a hippo resting in the water. I turned around to look back at the boat's wake and saw the hippo charging after us! The hippo must've been tired from an all-nighter because he was angry. He rose way up out of the water three times trying to chase our boat! He was coming at us with such force that he created a wake of his own. Photo location: Selinda Reserve of northern Botswana. (Photo and caption by Curtis Simmons/National Geographic Photo Contest)

A five-week-old orphaned Southern Sea Otter pup rests on a rubber mat after arriving at the Shedd Aquarium's Abbott Oceanarium in Chicago, Illinois October 28, 2014 in this handout photo provided to Reuters on November 5, 2014. The stranded pup was found on September 30 on Coastways Beach in California and was rescued the next day to be brought back to health at the Monterey Bay Aquarium. Southern sea otters were listed as “threatened” under the U.S. Endangered Species Act in 1977. (Photo by Brenna Hernandez/Reuters/Shedd Aquarium)

In this photograph taken on Thursday, November 20, 2014, bud tenders Maxwell Bradford, back left, and Emma Attolini display buds in the shape of Christmas trees that are on sale for the holiday season in a recreational marijuana shop in northwest Denver. The nascent marijuana industry in Colorado is targeting holiday shoppers with special deals much like traditional retailers offer. (Photo by David Zalubowski/AP Photo)

In this October 14, 2013 photo, ecology professor Ricardo Freitas catches a broad-snouted caiman to examine, then release back into the water channel in the affluent Recreio dos Bandeirantes suburb of Rio de Janeiro, Brazil. Caimans are like tanks, a very old species with a remarkable capacity for renovation that allows them to survive under extreme conditions where others couldn't, said Freitas, who runs the Instituto Jacare, or the Caiman Institute, which aims to protect the reptiles. (Photo by Felipe Dana/AP Photo)

The book “Elektroschutz in 132 Bildern” (Electrical Protection in 132 Pictures) was published in Vienna in the early 1900s by a Viennese physician named Stefan Jellinek (1878-1968, a founder of the Electro-Pathological Museum). The pictures are nice and direct and unambiguous; they teach, graphically, that the surest way to kill yourself with electricity is to form a complete path from source (usually the bright red arrow) to ground (the screened back, pink arrow). Arrowheads provide the path for current flow. (Photo by The Vienna Technical Museum)

A woman carries her child as she watches Mount Sinabung volcano spewing thick volcanic ash, as seen from Karo on July 21, 2017. Sinabung roared back to life in 2010 for the first time in 400 years, after another period of inactivity it erupted once more in 2013, and has remained highly active since. (Photo by Gatha Ginting/AFP Photo)

Femen activists with their bare chests reading “Fascists out of ballot boxes” are held back by Catalan regional police forces Mossos d'Esquadra as they protest against far-right Vox party candidates in Barcelona during regional elections in Catalonia on February 14, 2021. Catalonia is voting in an election overshadowed by the pandemic which Madrid hopes will unseat the region's ruling separatists more than three years after a failed bid to break away from Spain. (Photo by Lluis Gene/AFP Photo/Profimedia)