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 handout photo made available by TeideLab shows an image composed of 200 pictures that shows the lightning activity between 3 am and 7am during a storm in Izana, Tenerife, Canary Islands, Spain, 27 October 2019. Over 2,000 lighting strikes fell mostly over Tenerife island last 26 October during a strong storm. (Photo by Daniel López/EPA/EFE/TeideLab)

Afghans shout anti-U.S. slogans as they burn tires and block a highway during a protest in reaction to a small American church's plan to burn copies of the Quran, at Jalalabad, east of Kabul, Afghanistan, Friday, September 10, 2010. Religious and political leaders across the Muslim world welcomed a decision by the church to suspend its plans to torch copies of their holy book but some said Friday the damage has already been done. (Photo by Rahmat Gul/AP Photo)

A reveller sleeps on the pavement during the Sanja Matsuri festival in the Asakusa district of Tokyo May 17, 2015. The Sanja Matsuri festival attracts over about one million visitors over its duration of three days, when parties of revellers carry portable shrines through the Asakusa neighbourhood, rocking and shaking them in a belief that this intensified the powers of the deities that reside inside them. (Photo by Thomas Peter/Reuters)

These unique photos capture the moment a boy has his teeth picked clean by amazing underwater shrimp. These fascinating creatures spend their lives diving inside the mouths of fish to remove the parasites that lurk there. Russell Laman imitated the behaviour of the surrounding fish swarm to entice the cleaner shrimp into his mouth whilst snorkelling with his father Tim Laman in Bali, Indonesia. The 13-year-old queued with the waiting fish and then opened his mouth when the shrimps came near. (Photo by Tim Laman/Caters News)

Sikh devotee take part in Nagar Keertan procession on the occasion of Guru Gobind Singh birth anniversary in Allahabad, India on December 29, 2016. Guru Gobind Singh, born Gobind Rai (1666 – 1708), was the 10th Sikh Guru, a spiritual master, warrior, poet and philosopher. When his father, Guru Tegh Bahadur, was beheaded for refusing to convert to Islam, Guru Gobind Singh was formally installed as the leader of the Sikhs at age nine, becoming the last of the living Sikh Gurus. (Photo by Prabhat Kumar Verma/Pacific Press via ZUMA Wire/Rex Features/Shutterstock)

People walk down a makeshift modeling runway as they take a break from marching during the Brooklyn Liberation's Protect Trans Youth event on June 13, 2021 in the Brooklyn borough in New York City. Brooklyn Liberation organized a march and rally as an emergency action response to legislation to restrict trans rights across 34 states. According to the Human Rights Campaign, there have been over 250 bills introduced in state legislatures aimed at the LGBTQ community in 2021. (Photo by Michael M. Santiago/Getty Images)