Methane
From Halopedia, the Halo wiki
A gas that can be found on several planets in the universe. It is the gas that grunts breath, and is highly combustible. Teh fins on the back of the grunts are tanks that contain methane.
From Halopedia, the Halo wiki
A gas that can be found on several planets in the universe. It is the gas that grunts breath, and is highly combustible. Teh fins on the back of the grunts are tanks that contain methane.