A gargantuan and hideous long creature burrows its way up through the ground, the earth crumbling down its thick, oozy body in a collapsing mess. It has no legs, only a bulbous body and a mouth filled with sharp teeth. It opens its maw in a sound not unlike a wooden plank being torn apart, and the smell of rotting meat fills the air.
You are thrown to one side by the force of a gargantuan creature, with a thick grey hide, its tremendous maw so large and its saliva so energy charged that it passes through solid rock as a matter of course. Such a creature could, almost without effort, swallow your entire party in the blink of an eye.