Power core
From Halopedia, the Halo wiki
Power Cores are very similar to Fusion Cores and Plasma Batteries, except that they are Forerunner in origin. Their exact purpose is unknown but judging from its name it may serve as a power source. Power cores can be found mounted on walls in some Halo 3 Multiplayer maps. They are recognized by their low pulsating humming. They may be created from mines such as the Gas Mine in Halo 2, as that facility produced many similar power units. Template:Ratings