The nos monster was a carnivorous reptile native to the sinkholes of Utapau. Residing in the dank grottos deep underground, the aquatic nos' wide eyes were accustomed to the dark. Fiercely protective of its young, the nos would attack any threat it perceived. The varactyl and the nos may have shared an ancient evolutionary ancestor as both were native to the same world, and shared similarities between the two. Additionally, the nos monster was closely related to the swamp slugs of Dagobah. Nos monster ribs were served as a dish at Dex's Diner on Coruscant.