Related Clues:
- Mellows, maybe
- Large timeline segment
- Improves in the cask
- Astronomical stretch
- Gets older iron, and space-ice perhaps?
- Ice and Stone, e.g
- Long, long, long time period
- 'Rock of --'
- Vast span
- Census information
- Giga-year
- A billion years, in astronomy
- Reeeeeally long time
- An extremely long period of time
- Geologic-time measurement