Related Clues:

• Indefinable time
• Vast time frame
• Stretch of time
• Cosmic cycles
• 'It's been ___'
• It goes on and on and on
• Immeasurably long period of time
• Immeasurable periods
• Lengthy stretch
• Census numbers
• Shakespeare wrote of seven
• Billion years
• Geologic time period
• Candle counts
• They seem to last forever