In case you're serious with the sphinx question: in ancient Greek myth the entrance to the city of Thebes was guarded by a sphinx who would only let you through if you could solve a riddle, otherwise the sphinx would eat you. Which riddle that would be changes from story to story but the most famous one is along the lines of "What creature walks on four legs in the morning, two at noon and three in the evening?". This was eventually solved by king Oedipus who realized it was a human who crawls as a baby, walks on two legs as an adult and needs a walking stick as a third leg when they're old. Depending on which version you read, the sphinx was either so shocked by him solving the riddle that it threw itself from a cliff or was simply slain by him.