In this photo taken Tuesday, October 14, 2014, skulls and bones are stacked at the Catacombs in Paris, France. The subterranean tunnels, stretching 2 kilometers (1.24 miles), cradle the bones of some 6 million Parisians from centuries past and once gave refuge to smugglers. The site used to close at 5 p.m., but is now staying open until 8 p.m. The change is mainly aimed at allowing more people to visit and reducing long lines, since it can only hold a limited number of people at a time and visits can't be reserved in advance. (Photo by Francois Mori/AP Photo)

Typhoon Haiyan survivor Mariena Delacueva stands amongst the ruins of her families home on November 6, 2014 in San Antonio, Samar, Philippines. Mariena's looks after the property after her parents moved to Manila to find work so they can save enough money to rebuild the house. Residents of Leyte and surrounds are preparing for the 1-year anniversary since Super Typhoon Yolanda struck the coast on November 8, 2013, leaving more than 6000 dead and many more homeless. (Photo by Chris McGrath/Getty Images)

People look at home-made armoured vehicle look-alikes on a street in Shenyang, Liaoning province, November 12, 2014. A man surnamed Zhang and his friends converted two cars into these two vehicles, for his son, and will be displaying them on show at a local park. The cannons on the vehicles can fire paintballs and smoke shells, local media cited Zhang as saying. (Photo by Reuters/Stringer)

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.

People wearing masks and carrying supplies walk past a mannequin wearing a mask in downtown Barcelona, Spain, Saturday, March 14, 2020. Spain's prime minister has announced a two-week state of emergency from Saturday in a bid to contain the new coronavirus outbreak. For most people, the new coronavirus causes only mild or moderate symptoms. For some, it can cause more severe illness, especially in older adults and people with existing health problems. (Photo by Emilio Morenatti/AP Photo)

In a photo taken on April 2, 2020 a staff member feeds a raccoon at the Table A Raccoon Cafe in Seoul. Business has been devastated by the coronavirus outbreak, with South Koreans staying at home under social distancing guidelines, and tourism disappearing. But unlike other firms, animal cafes have to stay open so that staff can look after their stock. (Photo by Ed Jones/AFP Photo)

In this Monday, April 6, 2020 photo, a woman carries a her baby and a bucket of water in Harare. Lockdowns imposed to curb the coronavirus’ spread have put millions of women in Africa, Asia and elsewhere out of reach of birth control and other sexual and reproductive health needs. Confined to their homes with husbands and others, they face unwanted pregnancies and little idea of when they can reach the outside world again. (Photo by Tsvangirayi Mukwazhi/AP Photo)

This perfectly-timed GoPro snap captures the moment an angrymagpiecame within inches of a biker, as swooping season takes hold in Australia. The notoriously aggressive bird can be seen flying with its wings tucked in so it looks exactly like a torpedo in the magnificent photograph from Middlemount, Queensland. Retail businesswoman Monique Newton, 53 was riding pillion with a friend when she spied the divebombing bird – but rather than speed off, they slowed down to capture it up close. (Photo by Monique Newton/Caters News Agency)