Amulets in the shape of animal horns, such as the mano cornuto (the sign of the horns co-opted by 20th century metalheads but originally used as early as Ancient Rome as anti-witch gesture and/or talisman), and the horseshoe, have been used the world over as a protection against the evil eye and bringer of fortune. One of the most compelling theories as to why the arced shape in its various forms has been imbued with the power to shield the wearer from harm is that it that evokes the shape of the crescent moon, which many ancient cultures believed to influence the bounty of crops and have a significant effect on the events of everyday life.