The Triboniophorus Tyrannus, often referred to as the Brain Slug, is a community-created headwear item for the Pyro. Triboniophorus Tyrannus is a green, gelatinous slug with beady black eyes, placed off-center atop the Pyro's gas mask-burnished head. When players equipped with this item kill an enemy unassisted by another player, the killfeed shows everyone in Pyroland that it gets the assist, with its custom name if it has one.