Aegaeon and his brothers Gyges and Cottus are known under the name of the Uranids (Theogony of Hesiod 502), and are described as huge monsters with a hundred arms and fifty heads. (Apollodorus i. Theogony of Hesiod 149)
Most writers mention the third Uranid under the name of Briareus instead of Aegaeon, which is explained in a passage of Homer, who says that men called him Aegaeon, but the gods Briareus.
According to Hesiod (154, 617.), Aegaeon and his brothers were hated by Uranus from the time of their birth, in consequence of which they were concealed in the depth of the earth, where they remained until the Titans began their war against Zeus.
On the advice of Gaea Zeus delivered the Uranids from their prison, that they might assist him. The hundred-armed giants conquered the Titans by hurling at them three hundred rocks at once, and secured the victory to Zeus, who thrust the Titans into Tartarus and placed the Hecatoncheires at its gates, or, according to others, in the depth of the ocean to guard them.
The Scholiast on Apollonius Rhodius (i. 1165) represents
Aegaeon as a son of Gaea and Pontus and
as living as a marine god in the Aegean sea. Ovid (Met. ii.
10) and Philostratus likewise regard him as a marine god,
while Virgil reckons him among the giants who stormed Olympus,
and Callimachus, regarding him in the same light, places him
under mount Aetna. The Scholiast Theocritus calls Briareus one of
the Cyclops. The opinion which
regards Aegaeon and his brothers as only personifications of the
extraordinary powers of nature, such as are manifested in the
violent commotions of the earth, as earthquakes, volcanic
eruptions and the like, seems to explain best the various
accounts about them.