Rot Grub

Rot grubs run from 1/2 inch to 2 inches long, with rare giants of 3 inches, in shades from pale maggot white to dung brown. Two tiny antenna stubs on the head set them apart from ordinary maggots, but 75% of the time they are taken for common worms.

Bare skin touching a rot grub is burrowed into automatically, with no attack roll. If it is unclear whether skin was exposed, multiply the character's Armor Class (ignoring shields) by 10 for the percentage chance they made contact. The grubs numb the wound with an anesthetic, so the victim may feel nothing; a Wisdom check on 1d20 each round reveals the problem, and haste matters.

Burning the wound deals 1d6 to the victim and kills 2d10 grubs per application, while cure disease kills them all. Within 1d6 rounds they are too deep for flame to reach. Left untreated, they tunnel to the heart and kill the host in 1d3 turns.

Swarms infest dung heaps, offal, and, in swamps and jungles, rotting vegetation, so walking barefoot there is asking for it. They are rarely found in walls, floors, or ceilings, and ghouls, ghasts, zombies, and wights sometimes carry them unharmed. A dead host becomes a nest for eggs. They gather nothing, but there is a 1% chance of meeting them inside a fresh corpse, in which case its belongings use treasure types I, K, L, and M. Living flesh is their favorite, though they will eat carrion, plants, and worse.

Assassins value them: a grub or two on a sleeper means a quick, quiet death, and only a physician who knows the signs can name the cause. Giant ants, centipedes, and spiders eat them, and mind reavers, brinekin, trolls, and troglodytes snack on them like meal worms. Alchemists have failed so far to distill a usable anesthetic from them, and rumor says they serve as components in harmful reversed healing spells.