The Sphinx that guards Djelibeybi. It allows people to pass only by answering the riddle: What has 4 legs in the morning, 2 legs in the middle of the day, and 3 legs in the evening?
Otherwise it would eat them. The protagonist, Pteppic, is unable to answer the riddle, but is not eaten as he exploits flaws in the riddle.
The Sphinx lives in a separate plane of dimension just outside of Djelibeybi.