Epoch

Epoch, also called "The Wings of Time", is a time machine built by Belthasar in Chrono Trigger.

Break the Seal!
Unlocking the sealed doors in Keeper's Dome in 2300 A.D., Crono's party discovers the Epoch. The Nu, to which Belthasar downloaded his memory, tells them it's his last invention and explains how to use it.

So Crono's party takes it through time to once again reach 12,000 B.C.