Perseus, the legendary hero, used the Medusa head to petrify his enemies and from the Medusa's blood rose his winged steed, Pegasus, who was 'born of female wisdom.' In the Mediterranean, red coral jewelry is still associated with Medusa and menstral blood.
The image shown here is from an Italian Rennaisance shield. The face, all-knowing and wise, appears about to speak. Surrounded by her serpents and a solar halo, the figure was obviously utilized in the hope that Medusa would turn all enemies to stone.
Information above from Barbara Walker's The Woman's Dictionary of Symbols and Sacred Objects, 1988.