Napalm grenade

Historically, Napalm is a mixture of chemicals which, when mixed with gasoline, makes a sticky incendiary gel. Developed by the U.S. in World War II by a team of Harvard chemists led by Louis Fieser, its name is a combination of its original ingredient's names:
 * Aluminum salts of naphthenic and palmitic acids.

The name has since evolved from just the gasoline and Napalm gel, to mean any substance that causes intense fires upon ignition.

In the Halo Universe, the Firebomb Grenade was used by UNSC forces in the Halo Novels. It, however, is not in Halo 3, since its idea has been replaced by the Type-3 Grenade, used primarily by Brute Stalkers.