Medusa part of their religion. Medusa was beheaded by the hero Perseus, who thereafter used her head, which retained its ability to turn onlookers to stone, as a weapon until he gave it to the goddess Athena to place on her shield. In classical antiquity the image of the head of Medusa appeared in the evil-averting device known as the "Gorgoneion". The three Gorgon sisters—Medusa, Stheno, and Euryale—were all children of the ancient marine deities Phorcys (or "Phorkys") and his sister Ceto (or "Keto"), chthonic monsters from an archaic world. Their genealogy is shared with other sisters, the Graeae, as in
The Son of Neptune can only be defeated if the gods and the demigods join forces. This proves to be difficult. Percy and his friends manage to defeat the Alaskan Giant and save Camp Jupiter from destruction. During their journey, Hazel and Frank become true heroes who know how to use their powers and have self-confidence. Percy regains his memory on their return to Camp Jupiter and finds an army of monsters (including Stheno, Euryale, and the three Cyclopes) led by Polybotes attacking it. Percy successfully defeats him with the help of Terminus, his Cyclops half-brother, Tyson and the hellhound Mrs. O'Leary. At the