From Halopedia, the Halo wiki
A pentad was a Forerunner unit of time. One pentad equalled one-fifth of a Forerunner domestic year. How long this is in relation to Earth time is unknown.
List of appearances
- Halo: Cryptum (First appearance)
- ^ Halo: Cryptum, page 287
- ^ Halo: Cryptum, page 107