Faking Brutes
From Halopedia, the Halo wiki
On the Sacred Icon (Level), sometimes on Heroic mode, where you fight an Enforcer, there will be a body of a Brute close to the plug locks. When you deactivate the containment shield and the platform you are on begins to move, look at the Brutes eyes. THEY BLINK. Either they're zombie Brutes or they're faking! Someone please try and attempt this, because I'm not too sure if it'll work the second time around.
This is only one of the numerous times a body can seem "alive". If you have acquired the Sputnik Skull, and can find a body that blinks (namely Brutes), abuse the body by melee, and look closely at the eyes. It is speculated that the game engine beleives it is still alive, making the lifeless body blink. By moving it so violently with a Sputnik/Melee attack, you can activate this glitch.
It may also be another programming error; The same thing happens if you kill a talking German in the game Call of Duty 2.
