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.

A sloth peeks out from behind a door on a floating house in the “Lago do Janauari” near Manaus, Brazil, Tuesday, May 20, 2014. Manaus is one of the host cities for the 2014 World Cup in Brazil. (Photo by Felipe Dana/AP Photo)

View of a damaged bridge at the Iguacu Falls on June 12, 2014, in Foz do Iguacu, Brazil, following the overflowing of the Parana river. In neighbouring Paraguay flooding has forced the evacuation of about 150,000 people in Paraguay's capital city Asuncion, authorities said. (Photo by Norberto Duarte/AFP Photo)

A demonstration of Extinction Rebellion in Amsterdam, the Netherlands, has been dissolved by the local triangle (police, judiciary and mayor), February 26, 2021. About eighty activists, some of whom scantily dressed, blocked the Overtoom in Amsterdam-West. About twenty of them do not want to leave, they are taken away elsewhere. (Photo by Koen van Weel/EPA/EFE)

Pregnant revelers dance during a street pre-carnival party by the “Cordao do Boitata” Block, in Rio de Janeiro, Brazil, Sunday, February 12, 2023. Revelers are taking to the streets for the open-air block parties, leading up to Carnival's official Feb. 17th opening. (Photo by Bruna Prado/AP Photo)

Joy Corrigan is seen on June 24, 2021 in Los Angeles, California. The 26-year-old American supermodel wore a peach bra and matching shorts with a bright yellow handbag in LA for the Alo Yoga do. (Photo by The Mega Agency)

People look at a skeleton couple kissing installation dubbed “Till Death Do Us Part” during a Valentine's Day event in Bucharest, Romania, Tuesday, February 13, 2024. (Photo by Vadim Ghirda/AP Photo)

A man walks with a Cyberdog, produced by Chinese tech company Xiaomi, on February 19, 2022 in Beijing, China.The quadruped robots, often owned by tech and robotic enthusiasts, do not have a specific purpose so far, but the open source nature of the robots could make them suitable for several applications in the future. (Photo by Andrea Verdelli/Getty Images)