Measuring app. 7/8 (including ear wire) x 5/8 inch wide. Contemporary.
In Greek mythology, Medusa, a Gorgon, was a female monster with living serpents as hair. She would turn to stone anyone who looked upon her. Perseus was tasked with bringing her head to King Polydectes. Aided by the gods, he completed his task by using a mirrored shield given to him by Athena which he used to view Medusa's reflection. He then used her head as a protective weapon for the duration of his quest after which he presented it as a gift to Athena who placed it on her shield or aegis. The symbol of Medusas head on a shield became a popular talisman to protect the home in Rome. It continues to be used as a symbol of power and protection to this day.