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.

Mount Lewotobi Laki-laki volcano spews vulcanic materials during an eruption as seen from Pululera village in East Flores Regency, East Nusa Tenggara province, Indonesia, on April 27, 2025. (Photo by The Centre for Volcanology and Geological Hazard Mitigation (PVMBG)/Handout via Reuters)

Journalists report during a media tour near the volcano on the island of La Palma in the Canaries, Spain, Wednesday, September 22, 2021. A volcano on a small Spanish island in the Atlantic Ocean erupted on Sunday, forcing the evacuation of thousands of people. Experts say the volcanic eruption and its aftermath on a Spanish island could last for up to 84 days. The Canary Island Volcanology Institute said Wednesday it based its calculation on the length of previous eruptions on the archipelago. (Photo by Emilio Morenatti/AP Photo)

Schoolchildren run during the eruption of Mount Lewotobi Laki-Laki, as seen from Lewolaga village in East Flores, East Nusa Tenggara, Indonesia on November 7, 2024. (Photo by Arnold Welianto/AFP Photo)

This handout photograph taken and released by the Center for Volcanology and Geological Hazard Mitigation on April 17, 2024, shows Mount Ruang spewing hot lava and smoke as seen from Sitaro, North Sulawesi. A volcano erupted several times in Indonesia's outermost region overnight on April 17, forcing hundreds of people to be evacuated after it spewed lava and a column of smoke more than a mile into the sky. (Photo by Handout/Center for Volcanology and Geological Hazard Mitigation via AFP Photo)

A violent eruption spews ash more than a kilometer into the sky above Mount Etna in Sicily on February 23, 2021. (Photo by Marco Restivo/Barcroft Studios via Getty Images)

Mount Sinabung releasing volcanic ash, on February 04, 2017 Karo, North Sumatra, Indonesia. (Photo by Albert Damanik/Barcroft Images)

Mangrove in Walakiri Beach after Sunset in East Sumba, Indonesia in 2018. (Photo by Sarubabel Malau/Rex Features/Shutterstock)