Related Clues:
- Tons of time
- Megayears
- What a houseguest's stay might feel like
- Astronomer's time period
- Long time period
- Long interval
- 1,000,000,000 years
- One billion years, in geologic time
- Waiting period, it sometimes seems
- A billion years, geologically
- Division of geological time
- Long geological period
- Very long stretches
- An age
- Almost an eternity