Adder Stone

An Adder Stone, also known as a "Fairy Stone," is a type of stone, usually glassy, with a naturally occurring hole through it

Magical Properties

Adder stones were believed to have magical powers such as protection against diseases and evil charms, preventing nightmares, the ability to see through fairy or witch disguises and traps (if one looks through the middle of the stone), and recovery from snakebite. According to popular conception, a true adder stone will float in water.

Origins

Three traditions exist as to the origins of adder stones. One holds that the stones are the hardened saliva of large numbers of serpents massing together, the perforations being caused by their tongues. The other claims that an adder stone comes from the head of a serpent or is made by the sting of an adder. The third is more modern (and much easier to attain). It details that an adder stone can be made by letting water run over any variety of stone, so long as the stone is perforated. This must be a natural process, so human intervention is not allowed.