Red mercury has been held in mystical regard for centuries: From allegedly being buried with Egyptian royals in order to guarantee them an afterlife to the hushed reverence with which medieval alchemists spoke about it to cacophonous Internet pop up ads blaring about its panacea qualities.

Some modern incantations have the substance manifesting itself in vampire bat nests. Unintentionally comedic YouTube videos show a blob of supposed red mercury being repelled by garlic, attracted by gold, and showing no reflection.
In truth, there are no bat nests. The winged mammals instead cling to walls, rafters, and cave dwellings when needing to rest or sleep. Of more importance with regard to this topic, there also is no red mercury elixir. The only red-hued mercury is mercury sulphide, whose main use is in pottery decoration and to which no healing abilities are attributed.

While much less cool than pharaoh tombs or hypothetical vampire bat nests, Singer sewing machines have also been reported to house red mercury. The ridiculous rumor was apparently started by someone who found it a convenient avenue to unload his surplus sewing machines for 2,000 times their worth.

While usually associated with healing, red mercury tales have darker versions that tie it to nuclear weapons or bomb making. These began making the rounds when eastern European communism collapsed. This time of upheaval and uncertainty, combined with legitimate concern about what would become of nuclear stockpiles, led to wild speculation that red mercury was a necessary element to the weapons and that this destructive force about to be purloined by terrorist outfits or unleashed by a government desperate to stay in power. The rumor may have begun since red mercury is a nickname for a certain nuclear isotope. 

Terrorists have apparently tried to make the rumors come true. In 2015, Islamic State members were arrested after attempting to buy red mercury, though exactly what it is they were buying and what their plans were for it are unclear since the substance doesn’t exist.