Slug Prince

The Slug Prince is encountered in the Witchaven Dungeon during The Slug Menace quest. He can only be fought once and requires 30 Slayer to kill. The people of Witchaven are obviously very mad at you for killing the Slug Prince, as after you kill him they tell you to leave them alone.

Fighting
The Slug Prince can only be fought with melee; using Ranged or Magic is futile, as they bounce harmlessly off. However, he is very easy, and high and medium level players can kill him without prayer or food. If you do choose to use Protect from Melee, be aware that the Slug Prince's attacks may drain Prayer. A high or medium levelled player should have little to no problems fighting him, but lower levels might want to bring food or even prayer potions. A ring of recoil and a serpentine helm do not work against the Slug Prince.

Appearance
The Slug Prince's appearance is a small, shell-like body, with one mouthlike object protruding from the front. Its appearance is similar to that of a hermit crab.

The Prince is no bigger than the player's character, which might mean the prince is a larva of some sort, and that there are other slugs that are Mother Mallum's size.

Trivia

 * Although the Slug Prince doesn't drop anything, he leaves behind "Slug goo", with the examine text "Exploding goo." and remains so even through Mother Mallum's cutscene.