Cronus was the Titan tricked into swallowing a stone instead of his son Zeus.
Cronus had received a prophecy that one of his children would overthrow him, just as he had overthrown his own father, Uranus. To prevent that fate, he swallowed each child born to his sister-wife Rhea: Hestia, Demeter, Hera, Hades and Poseidon.
When Zeus was born, Rhea refused to surrender him. She hid the infant in Crete and wrapped a stone in swaddling clothes, presenting it to Cronus as the newborn child. Cronus swallowed the stone without realizing the deception. Zeus later grew up, forced Cronus to disgorge his swallowed siblings and led the Olympians against the Titans in the Titanomachy.
The stone is sometimes described as the Omphalos, a sacred object later associated with Delphi, although ancient accounts and later traditions vary in how they connect the two. Rhea is the trickster in this episode, not Zeus: Zeus was the concealed child. Cronus is also distinct from Chronos, the personification of time, despite the similarity of their names in English.