These are Jewish pendants of protection against the demon Lilith. In “The Alphabet of Ben Sirach”, a medieval Jewish text, the legend appeared of Lilith as the first wife of Adam who refused to have sex in a submissive position – because she chose to leave Adam rather than submit, 100 of her demon children a day would die, and Lilith would try to kill infant descendents of Adam ever after. Pendants like these were popular among Esstern European Jews.