Bloodworms are a species of yellowish-reddish, leech-like creatures that lurk in the Barrows tunnels where they live in the darkness and feed on the blood of unwary treasure hunters. Bloodworms are one of the many obstacles between a player and the chest containing rewards where they constantly distract players from completing puzzles. As with all monsters in the crypts, they are aggressive to any player regardless of their Combat level. They are commonly killed alongside two skeletons each run as a quick way to optimise the player's reward potential for the most runes. They may spawn whenever the player opens a door in the tunnels.
Killing a bloodworm will increase the player's rewards potential by 52.