Small (4-10 inches) invertabrates creatures found in the swamps of the Zemuni Islands. Kept as pets by the Tirin' Kor to clean their scales they are natural scavengers who effectively eat the dirt, grime and dead and infected tissue. Even the poorest Tirin' Kor have a yesleth slug. Life without one is impossible as so many health complications occur due to easily correctable problems.

Forming a symbiotic relationship with their Tirin' Kor some yesleth slugs are protective of their masters and will spray a temporarily blinding toxin at an enemy who threatens them. Aside from feeding off the Tirin' Kor itself many allow their slugs to feed on the carrion of foes on the battlefield. Each slug leaves its own indivisual musk so that it can return to its owner.