The Core Muncher is an animal that burrows through a planet's crust. Zim explains to his intern "Derb" (actually Dib in disguise), that he got the Core Muncher at a Bazoogian Bio-Swap and Crafts fair. He further states that he's hollowed out its brain and implanted a control bubble, and that he intends to use it to create new volcanos all over the Earth. It is unknown if the Core Muncher survived this experience.