He was the son of Poseidon (or Uranus) and Gaea.
In Greek mythology the term was specially applied to the stone supposed to have been swallowed by Cronus (who feared misfortune from his own children) in mistake for his infant son Zeus, for whom it had been substituted by Uranus and Gaea, his wife's parents (Etymologicum Magnum, s.v.).
The Attic tradition, reproduced in Euripides (Ion 1002), regarded the Gorgon as a monster, produced by Gaea to aid her sons the giants against the gods and slain by Athena (the passage is a locus classicus on the aegis of Athena).
In the beginning (as in the Greek myths of Uranus and Gaea), Heaven (Rangi, conceived of as a person) was indissolubly united to his wife Earth (Papa), and between them they begat gods which necessarily dwelt in darkness.
Then followed the wars between Zeus and the gods he had rescued from the maw of Cronus against the gods of the elder branch, the children of Uranus and Gaea - Heaven and Earth.