Fire beetle

Fire beetles are giant insects capable of delivering serious damage with their powerful mandibles. They are found both above and below ground, and are primarily nocturnal. Despite its name, the fire beetle has no fire attacks.

Fire beetles have two special glands above their eyes and one near the back of their abdomens. These glands produce a luminous red glow, and for this reason they are highly prized by miners and adventurers. This luminosity persists for several days after the glands are removed from the beetle, and the light shed will illuminate a radius of 10 feet.

The light from these glands is "cold" -- it produces no heat. Many mages and alchemists are eager to discover the secret of this cold light, which could be not only safe, but economical, with no parts to heat up and burn out. In theory, they say, such a light source could last forever.

Note: Fire beetles originally appeared in this form in the 2nd Edition Monstrous Manual for the AD&D game from TSR. Their use here is for the purposes of providing context for the campaign only.