No Stone Unturned (achievement)

No Stone Unturned is an achievement in Halo: The Master Chief Collection. It is awarded for activating all eight of the Terminals in Halo 3. The achievement is worth 20 Gamerscore and can be unlocked on any difficulty. The player must scroll through and access both parts of the terminals to unlock the achievement.

Unlike the Marathon Man achievement in the original game, players must activate all seven regular terminals as well as the secret Cortana terminal in order to complete this achievement. Viewing the communique from Mendicant Bias and unlocking the Whispers Across the Galaxy achievement is not required.