Gorgoneion

Myths, folklore, & symbolism
Gorgoneion: The head of a Gorgon, which had a grotesque, horrific appearance with an open maw, bared teeth, protruding tongue, and often a beard. It is a symbol of the terrifying aspect of divine powers and an apotropaic sign affixed to temples; a Gorgoneion is also affixed to the center of the aegis. (Herder)