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Related Clues:
- Gigayear
- Forever and a day, facetiously
- It's a real stretch
- Astronomically long time
- It seemingly never ends
- Long, long times
- Hundreds of centuries
- 1,000,000,000 years, in geology
- Vast timeframe
- Long historical episode
- Long stretch of time
- About a billion years
- Unit in astronomy
- Mind-boggling time
- Million-millennia period