Graeae
The Graeae, also called the Grey Sisters and the Phorcides, were three sisters of Greek mythology who had gray hair from their birth and shared one eye and one tooth among them. They were the daughters of the primordial sea gods Phorcys and Ceto and sisters of, among others, the Gorgons. Their names were Deino, Pemphredo, and Enyo. They are best known from their encounter with Perseus, who, after capturing their eye, forced them to reveal information about the Gorgons.
Etymology
The Greek Graiai is derived from the Proto-Indo-European root ǵreh2-, "to grow old" via.Mythology
The Graeae were daughters of the sea-deities Ceto and Phorcys and sisters to the Gorgons. The Graeae took the form of old, grey-haired women. Their age was so great that a human childhood for them was hardly conceivable. In Theogony, however, Hesiod describes the Graeae as being "fair-cheeked". In Prometheus Bound, the Graeae are described as being "ancient maidens of swan-like aspect".Hesiod names only two Graeae, the "well-clad" "Pemphredo" and the "saffron-robed" Enyo, while Apollodorus lists Deino as a third. Calling them "Phorcides", Hyginus, in addition to Pemphredo and Enyo, adds Persis, noting that "for this last others say Dino".
They shared one eye and one tooth, which they took turns using. By stealing their eye while they were passing it among themselves, the hero Perseus forced them to tell the whereabouts of the three objects needed to kill Medusa by ransoming their shared eye for the information.