Related Clues:

• '___ Flux' (MTV cartoon)
• An age
• Almost an eternity
• It keeps going and going ...
• Many many years
• A million millennia
• Untold millennia
• Video game “__ Flux”
• The Phanerozoic, e.g.
• See 41 Down
• Era after era
• It's split into eras
• Very long time unit
• Quite a long time
• It's longer than an era