The stone Rhea tricked Chronos into eating, thinking it was their sixth child, Zeus, is known in mythology as the Omphalos Stone. In Greek, the world Omphalos means “Navel”, hence the name of the exhibit where the stone artifact sits today, in the Temple of Apollo in Delphi: “The Navel of the World”. When Zeus grew old enough to challenge his father Chronos, he famously forced his father to regurgitate the contents of his stomach, from which escaped the five siblings Chronos had eaten before Zeus’ birth, and the stone he was tricked by Rhea into believing was Zeus himself.
Another Greek myth postulates that Zeus set two eagles at opposite ends of the world, and commanded them to fly until they again found one another. Their meeting point is said to be Delphi, precisely where Zeus put the Omphalos stone, the Navel of the World; the Ancient Greeks would come to believe, based on this myth, that Delphi was the center of the world.