Ceto (Κητώ) (Kētṓ) means 'sea monster'. She was a sea goddess in Greek myths and legends. Ceto's parents were Pontus (Πόντος) (Póntos) and Gaia (Γαῖα) (Gaîa).
Phorcys (Φόρκυς) (Phórkos) was her consort. They had children: the Gorgons (Γοργώνες) (Gorgones), the Graeae (Γραῖαι) (graîa), Echidna (Ἔχιδνα) (Ékhidna), and Ladon (Λάδωνος) (Ladonos). The Nemean lion (Νεμέος λέων) (Leo Nemeaeus) and the Sphinx (σφίγξ) (phíx) were Ceto's children, too.
Also, Ceto had several siblings.
"They are two sisters: one gives birth to other, who in turn gives birth to the first. Who are the two sisters?" the Sphinx asked Oedipus.
"These two sisters are day (ἡμέρα) and night (νύξ)." Oedipus answered.
The Sphinx had this riddle, too.
After that, she killed herself.
The creature Sphinx (Σφίγξ) guarded Thebes (Θῆβαι), the Greek city. Typhon (Τυφῶν) and Chimera (Χίμαιρα) were her parents. Hera (Ἥρα) or Ares (Ἄρης) sent her in this place. The Sphinx had her own riddle. It sounds like this:
"Which creature has one voice and yet becomes four-footed and two-footed and three-footed?"
She killed who couldn't answer this question.
Oedipus (Οἰδίπους) solved the riddle of Sphinx.
"Person-who crawls on all fours as a baby, then walks on two feet as an adult, and then uses a walking stick during old age," he answered.
Afterwards, the creature killed herself.
Later Oedipus became the king of Thebes.
This riddle is popular in culture and art.
