An omphalos is a religious stone artefact. In Ancient Greek, the word ὀμφᾰλός means "navel". Among the Ancient Greeks, it was a widespread belief that Delphi was the center of the world. According to
The Omphalos of Delphi
Omphalos of Chiang Rai, Thailand.
In ancient Greek religion and mythology, Cronus, Cronos, or Kronos was the leader and youngest of the Titans, the children of Gaia and Uranus. Cronus castrated and overthrew his father and then ruled
Omphalos
…was the place where Zeus placed the stone. The Latin term is umbilicus mundi, 'navel of the world'. Omphalos is also the name of the stone given to Cronus. Most accounts locate the Delphi omphalos in the adyton (sacred part of the temple) near the Pythia (oracle). The stone sculpture itself, which may be…
Rhea offers to Cronus a stone wrapped in swaddling clothes, in place of the newborn Zeus. Red-figure ceramic vase, c. 460–450 BC, Metropolitan Museum of Art.
The Mutilation of Uranus by Saturn [Cronus], 16th-century oil painting by Giorgio Vasari
Cronus devouring one of his sons, 17th-century oil painting by Peter Paul Rubens
Rhea giving the rock to Cronus, 19th-century painted frieze by Karl Friedrich Schinkel