Leviathan grubs, omnivorous creatures dwelling underground, originated from the moon Yavin 4 and were categorized as a species. These grubs subsisted on the subterranean roots of Massassi trees for a period of three hundred years. Subsequently, they would surface to become among the largest predatory organisms inhabiting the moon's forests.
The initial mention of leviathan grubs occurred in the reference publication titled Ultimate Star Wars, which saw its release in 2015.