Power core

Power Cores are very similar to Fusion Coils, Gas containers and Plasma Batteries.

Their purpose may be to store plasma energy to power up Forerunner machines. When a Power Core explodes, it is lethal. Power cores can be found mounted on walls in the Campaign levels, as well as in some of Halo 3's Multiplayer maps. They are recognized by their low pulsating humming. These can be used to kill anyone who passes by if they are shot at. However, it takes two Power cores explosions combined to kill somebody with shields. In Halo 3, certain maps can spawn the Power Core in Forge.

Trivia

 * The Power Core is the least seen object in the Halo series in Campaign.
 * They may be created from mines such as the Gas Mine in Halo 2, as that facility produced many similar power units.
 * It is comparable that the Power Core is the Forerunner surrogate and equivalent for the Covenant Plasma Battery and the UNSC Fusion Coil.
 * They are first seen on Halo 2 multiplayer map Lockout.
 * There are a pile of Power Cores in Construct.