Hundreds of meters in length, the zillo beast is a subterranean creature with an incredibly hard carapace. Even heavy artillery and lightsabers were unable to penetrate its hide. It is strong enough to lift heavy tanks. It has five limbs and a spiked tail, generally walking on two "legs" and using two "arms" for manipulation, with a third "arm" protruding from its back, largely unused.
While essentially invulnerable to conventional weapons, it could be subdued with powerful stun rays that penetrated the gaps between its scales or poisoned with a type of fuel made on Malastair.