What is Medusa in greek mythology?

In Greek mythology, Medusa is a monster, a Gorgon, one of three monstrous sisters known as the Gorgons. According to Hesiod and Aeschylus, she was one of the three monstrous Gorgons, born of Phorcys and Ceto; later myths make her the daughter of the sea god, Phorcys and a gorgon. The Gorgons lived at the westernmost edge of the world, near the edge of night—in the land surrounding night's Hespereides daughters.

According to most legends, Medusa was originally a beautiful maiden that Poseidon seduced in Athena's temple. As punishment, Athena turned Medusa and her two Gorgon sisters into monsterous and ugly creatures as they had previously possessed great beauty. It is also said that her gaze alone, due to Athena's curse, transformed all living creatures into stone and that her head remained a powerful talisman. Other mythologies say only one of the sisters, Stheno, could do that so Medusa may originally have not had that unique attribute. Perseus famously slew Medusa by using a mirrored shield to avoid looking directly at her and decapitated her while she slept. The myth states he used winged sandals given to him by Hermes to escape her pursuing sisters. Other legends state he simply outran them. It is said Poseidon took the drops of blood spilling from her dead body and placed them onto corals and sea plants which was what gave them colour to them