"Aegis, the shield Perseus used to defeat the Gorgon Medusa"

Because the gaze of Medusa turned all who looked at her to stone, Perseus guided himself by her reflection in a shield given him by Athena and beheaded Medusa as she slept. He then returned to Seriphus and rescued his mother by turning Polydectes and his supporters to stone at the sight of Medusa’s head.

A further deed attributed to Perseus was his rescue of the Ethiopian princess Andromeda when he was on his way home with Medusa’s head. Andromeda’s mother, Cassiopeia, had claimed to be more beautiful than the sea nymphs, or Nereids; so Poseidon had punished Ethiopia by flooding it and plaguing it with a sea monster. An oracle informed Andromeda’s father, King Cepheus, that the ills would cease if he exposed Andromeda to the monster, which he did. Perseus, passing by, saw the princess and fell in love with her. He turned the sea monster to stone by showing it Medusa’s head and afterward married Andromeda.