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 two-week-old hoglet finds an unusual spot to sit at the Happy Hedgehogs rescue centre in Nidderdale, North Yorkshire in the second decade of September 2023. (Photo by James Glossop/The Times)

In this Saturday, June 24, 2017 file photo, Zeid Ali, 12, left, and Hodayfa Ali, 11, comfort each other after their house was hit and collapsed during fighting between Iraqi forces and Islamic State militants in Mosul, Iraq. The Ali cousins said some of their family members are still under the rubble. (Photo by Felipe Dana/AP Photo/File)

Canada's Mandy Marchak (R) is taken down by France's Pauline Biscarat during the final match of the Hong Kong Sevens rugby women's invitational cup in Hong Kong March 28, 2014. (Photo by Tyrone Siu/Reuters)

Majesty Davis, 3, cries while visiting Santa Claus, who sits behind a plexiglass divider due to the coronavirus disease (COVID-19) pandemic, at the Willow Grove Park Mall in Willow Grove, Pennsylvania, U.S. November 14, 2020. (Photo by Mark Makela/Reuters)

American actress Kathryn Newton during the Chloe Ready to Wear Fall/Winter 2024-2025 fashion show as part of the Paris Fashion Week on February 29, 2024 in Paris, France. (Photo by Victor VIRGILE/Gamma-Rapho via Getty Images)

A young woman shows off her henna tattoos at the end of Eid al-Fitr prayers in Bucharest, Romania, Wednesday, April 10, 2024. Members of the Romanian Muslim community joined prayers at the Dinamo stadium in the Romanian capital, in the largest Muslim public gathering of the year. Eid al-Fitr marks the end of the holy fasting month of Ramadan. (Photo by Andreea Alexandru/AP Photo)

Eight-year-old handicapped Chinese girl Qian Hongyan crawls with two home-made props and part of a basketball at Zhuangxia Village on January 5, 2005 in Luliang County of Qujing City, Yunnan Province, China. The girl who lost both of her legs in a traffic accident in 2000 at the age of three, struggles to live her life with a basketball as an underprop, “walking” between school and home by herself. The girl's story is widely reported in the country, and experts from China Rehabilitation Research Center has come to Qian's home to help her for rehabilitative treatment early 2005. (Photo by China Photos/Getty Images)