Graeae

They were three sea hags who personified the white foam of the sea. They were grey-haired from birth and shared amongst themselves a single, detatchable eye and tooth. The hero Perseus stole these when he was searching for the Medusa, compelling the hags to reveal the location of their sister.

Parents: Phorcys and Ceto
Siblings: The Gorgons

Perseus and the Graeae by Edward Burne-Jones (1892).