Acid Slugs
Acid Slug, from Ultima VII manual
First appearance: Ultima VI
Last appearance: Serpent Isle

Acid Slugs are basically huge slugs. What makes them dangerous is implied by their name; they attack any being they sense near them with a strong, poisonous acid, which can destroy weapons and armor and cause horrible burns on the skin. Acid slugs however are very susceptible to fire, and a lit torch is most times enough to destroy them.

Acid slugs are only found in dungeons, caves and swamps.

While their behavior is always the same, the looks of the Acid Slugs changed quite often. In Ultima VI, they looked like pink blobs. In the Underworlds, they looked like green slugs. In Ultima VII and Ultima VII Part Two: Serpent Isle, they looked like white slugs.


Though seldom encountered except in the darkest corners of the dampest caves, this featureless creature will secrete its corrosive juices on anything you possess that is metal, thus dissolving it. Painful but superficial skin burns may result from contact with the acid while it eats away at your armour. Conventional weapons have little effect on the monster, whereas a flame will send it fleeing.

- from Compendium (Ultima VI)

Not to be mistaken for the common Slimes of Britannia, the Slugs of the Abyss are gelatinous, amorphous entities. Their extremely small and limited minds are entirely taken up with an insatiable curiosity, and so Slugs are certain to follow any motion they detect. Fortunately for explorers, Slugs have no eyes or ears, and therefore miss much that occurs around them. Of the two varieties of Slug found locally, the Flesh Slug - notable for its pale fleshy color - is the most common and least dangerous. We are not certain if these creatures intend to bite their victims, or if their offensive actions are accidents of their constant writhing. Certainly, no warrior of any experience need fear these pitiful beasts. However, beware the greenish Acid Slug. Though only a little larger than the Flesh Slug, the Acid Slug secretes a noxious vapor which sometimes intoxicates its foes. Despite its fearsome name, this Slug is not poisonous - merely inedible.

- from Memoirs of Sir Cabirus (Ultima Underworld)


This very unpleasant creature tends to inhabit dark places underground. Its skin exudes secretions of acid that can burn flesh and are especially damaging to metal. The best weapon to use against this monster is fire.

- from The Book of Fellowship (Ultima VII)

Slugs are little to be feared, only avoided. They writhe mindlessly and senselessly from place to place, feeding on whatever they encounter. Disgustingly enough, the flesh slug is a large amorphous blob of gelatin, the color of pale pink human flesh. The greenish acidslugs are slightly more dangerous, as they are capable of spitting acid a considerable distance.

- from A Safe Passage Through Britannia (Ultima Underworld II)

Much larger than its cousin, the common slug, the acid slug prefers habitats far below ground. The creature's slimy covering is quite acidic, burning easily through metal and flesh alike. If it is like its Sosarian counterpart, fire is the most potent way in which to combat one.

- from Beyond the Serpent Pillars (Ultima VII Part Two)