If we were to burn NH4Cr2O7 with HgSCN in the Dark Ages in Europe and show it to anyone, it is us who would be burning next on a fiery cross of Inquisition. And it’s no wonder, since this experiment produces a truly marvelous result. At first, as you ignite the mixture of NH4Cr2O7 and HgSCN, all you can see is that it is slowly burning with a reddish flame. After a while, however, a crater is formed in the middle of the burning pile, and then, suddenly, tentacle-like appendages start sprouting from the burning mixture. And you can almost hear the scream of the mad occultist – “Come forth, Kraken! Come forth!” But of course, this is simply a chemical reaction that is called the "Pharoah's Serpent". It was also often sold in firework stores until people realized that it was toxic.

Behishta,11, listens during 4th grade class at the Zarghoona high school on July 25 2021 in Kabul, Afghanistan. The Zarghoona girls high school is the largest in Kabul with 8,500 female students attending classes. The school opened after a nearly two-month break due to the coronavirus (COVID-19) pandemic. (Photo by Paula Bronstein/Getty Images)

Workers stir hundreds of large ceramic pots as they spend months making a traditional soy sauce on October 14, 2020. Arranged in rows, the containers can hold up to 50 litres of Ban Soy sauce. During the drawn out process the sauce is stirred every two days for two to six months. Ban Yen Nhan village in the Hung Yen Province of Vietnam is famous for its traditional and distinctive method of making the sauce. (Photo by Nguyen Quy/Solent News)

“The knight and his steed”. This picture was taken in a natural but controlled environment. There are pictures that can not be done in nature or that would imply a very high cost of both time and money, thats why photography workshops are run conducted at strategic locations and bringing EVERYONE who is interested, the basic notions (lighting, camera handling, composition, etc...) or the specimens, and afford them the opportunity to take pictures like this. Although controlled, this shot was not prepared at all, I was performing a workshop with the agalychnis callidryas treefrog from Costa Rica when the frog managed to jump to the branch where this huge titan was sleeping... I had my gear ready so I only had to change a few settings and shoot... the rest is history. (Photo and caption by Nicolas Reusens Boden (Sweden)/2014 Sony World Photography Awards)

An adorable baby koala is seen enjoying a snooze after a traumatic start to life. The baby koala, nicknamed “Blondie Bumstead”, is being cared for by a volunteer from the Ipswich Koala protection society in Queensland after her mother was killed by a dog. Blondie, who was named for her light fur, was given just a 50-50 chance of pulling through after the attack. But after a course of antibiotics and some tender loving car from volunteer Marilyn Spletter she has now been given a clean bill of health. According to Marilyn she has hand-reared around 40 baby koalas but says that Blondie, who will be released back into the wild after 15 months, is one of her favourites. She said: “She's got a little character all of her own and she knows what she wants and what she doesn't. When she's stressed I kiss her on the nose or I rub my nose on hers and it relaxes her”. (Photo by Jamie Hanson/Newspix/REX Features)

A jogger is seen running at Hampstead Heath with London in the background on June 1, 2021. Britain sees temperatures increasing for the second day in a row after the mercury hit 25C (77 Fahrenheit) for the warmest day of the year so far on Bank Holiday Monday. (Photo by Joshua Bratt/London News Pictures)

Growing cities, overuse of fertilizers and factory wastewater have degraded China's water supplies to the extent that half the nation's rivers and lakes are severely polluted. China aims to spend $850 billion to improve filthy water supplies over the next decade, but even such huge outlays may do little to reverse damage caused by decades of pollution and overuse in Beijing's push for rapid economic growth. Photo: Fishermen row a boat in the algae-filled Chaohu Lake in Hefei, Anhui province, June 19, 2009. (Photo by Jianan Yu/Reuters)

Rowers enter in Canaregio river during the 42nd Venice Vogalonga on May 15, 2016 in Venice, Italy. 42 years ago a group of Venetians, both amateur and professional rowers, came up with an idea of non-competitive race in which any kind of rowing boat can take part. The first Vogalonga began with the message to protest against the growing use of powerboats in Venice and the swell damage they do to the historic city. (Photo by Awakening/Getty Images)