Bloodworms

Bloodworms, the meaner cousins of Rotworms. The green Bloodworm is in many aspects like a Rotworm, but it is longer (up to three feet!) and very poisonous. Thus it is often found near water or swamps.

Found mostly in swamps or underground.

Lore
''These repulsive green crawlers are distantly related to the common Rotworms of Britannia, but are possessed of an aggressive nature that would befit a creature ten times their size. Sir Broderick stumbled upon a subterranean nest of these vermin, and quickly discovered that they were not as easily killed as Rotworms. Seeking to find a better location to make his stand against the beasts, the Knight retreated - only to discover the worms pursuing him with single-minded determination. Broderick finally slew them all, only to die from poisoning of the blood as a result of the worms' venom. His scrawled notes, written as a selfless act by a dying man, were recently recovered by explorers, but the good knight's body has never been found.''

- from "Memoirs of Sir Cabirus", Ultima Underworld

''Bloodworms are a revolting menace. They are large (up to three  feet long)  carnivorous green worms, usually found underground but  which occasionally squirm their way up to the surface. They are mindlessly  aggressive,  and  will  attack anything living, regardless  of  its  size. Although the bloodworm is easily killed, its bite is extremely venomous; more than one knight has died of it, thinking himself invulnerable to attacks by such lowly vermin.''

- from "A Safe Passage through Britannia", Ultima Underworld II