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 drone operated by paramilitary police flies over the site of last week's explosions at Binhai new district in Tianjin, China, August 17, 2015. Many operations have resumed at China's Tianjin port, trade sources said, after explosions last week that killed more than 100 people and disrupted business at what is an important oil, gas and bulk import harbor for Asia's biggest economy. The explosions on August 12 led to the disruption of all chemical and oil tanker discharges at the port, and imports of iron ore were also affected. (Photo by Kim Kyung-Hoon/Reuters)

A dog sits in a plastic tub filled with water in Taipei, Taiwan, 28 July 2020. Betel nut seller Mr Luo, the dog's owner, said he puts his dog, a 12-year-old mixed breed called Ah Dai (Stupid), in a plastic tub filled with water whenever the weather gets hot. Ah Dai enjoys the bath and can sit in the basin for hours, according to Mr Luo. Luo has a dozen pairs of glasses for Ah Dai, so the dog wears different glasses every day and many tourists take photos of Ah Dai. (Photo by David Chang/EPA/EFE)

Women carry gas cylinders to fill them at a distribution point in Cairo January 19, 2015. Egypt is going through its worst energy crisis in decades and is seeking fresh sources of natural gas, which powers most of its homes and factories. (Photo by Mohamed Abd El Ghany/Reuters)

A young Iraqi shepherdess cools down buffaloes in wastewater filling the dried-up Diyala river which was a tributary of the Tigris, in the Al-Fadiliyah district east of Baghdad, on June 26, 2022. (Photo by Ahmad Al-Rubaye/AFP Photo)

Vinaya Vijay, right, and Vijay Parthasarathy wade through water at Badwater Basin, Thursday, February 22, 2024, in Death Valley National Park, Calif. The basin, normally a salt flat, has filled from rain over the past few months. (Photo by John Locher/AP Photo)

Russian artist Oleg Kulik installs the wax figure resembling to Russian tennis star Anna Kournikova at his new exhibition project in Moscow on October 19, 2002. Kulik plans soon to fill his museum with figures of strong and beautiful women like Bjork and Madonna in unexpected poses. (Photo by Alexander Natruskin/Reuters)

Mohammad Ramzan, 60, a traditional goatskin water carrier also known as a mashki, fills a bag with water from a handpump to deliver to nearby homes during the fasting month of Ramadan, as the outbreak of the coronavirus disease (COVID-19) continues, in Karachi, Pakistan on April 23, 2021. (Photo by Akhtar Soomro/Reuters)