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 man dressed in a condom costume walks at Caleta Portales beach, during a summer awareness campaign by the Chilean Corporation for the Prevention of AIDS in Valparaiso city, northwest of Santiago January 9, 2015. (Photo by Rodrigo Garrido/Reuters)

A woman looks on while a horse-drawn carriage passes by Italian artist Emilio Ferro's artwork installation “Portal of Light” at the Giza pyramids necropolis during the second edition of the Art D’Égypte exhibition “Forever is Now” on October 27, 2022. (Photo by Khaled Desouki/AFP Photo)

In this photo taken on June 16, 2019 Indian stuntman Chanchal Lahiri, known by his stage name “Jadugar Mandrake”, is lowered into the Ganges river, while tied up with steel chains and ropes, in Kolkata. An Indian magician who went missing after being lowered into a river tied up in chains and ropes in a Houdini-inspired stunt is feared drowned, police said June 17. (Photo by AFP Photo/Stringer)

“Rivers Forgotten” is a journey through the passages and portals of the underground waterways that lie unseen below cities. Self-taught photographer Jeremy Kai brings these forgotten landscapes to light. Photo: Beneath the Toronto area, 2011. (Photo by Jeremy Kai)

Artists perform during the opening show directed by German director Volker Hesse, on the opening day of the Gotthard rail tunnel, at the fairground Rynaecht at the northern portal in Erstfeld, Switzerland, Wednesday, June 1, 2016. The construction of the 57 kilometer long tunnel began in 1999, the breakthrough was in 2010. After the official opening on June 1, the commercial operation will start in December 2016. (Photo by Ruben Sprich\Pool Photo via AP Photo)

Street art started out as unintelligible words written on concrete walls with spray paint by gang members or silly kids. Now, however, it evolved into a unique form of art that might stun and inspire awe in the onlookers. For example, the artist that goes by the name 1010 specializes in creating optical illusions. His creations look like portals into other dimensions, without any hint that it might simply be a flat concrete wall painted over with multicolored paints. These pieces of art are so good that it is hard not to reach out into these ‘holes’ to find out whether or not they are real. (Photo by 1010)

A worker of the Pakistan Bureau of Statistics (PBS) collects data for the digital census, in Karachi, Pakistan, 01 March 2023. PBS has launched a digital census and portal to allow citizens to submit their data. The census that began on 01 March, will be used for the upcoming general elections. So far, 4.3 million people have registered. (Photo by Shahzaib Akber/EPA/EFE)