Check out the Worm of Ghroth, a new monster from Sandy Petersen’s Cthulhu Mythos for Pathfinder 2nd Edition.
The worms of Ghroth are created by Ghroth’s influence, lingering behind when it departs to consume the reality Ghroth passes near. Worse, the worms of Ghroth can be summoned or gated from another world to one’s own, though the only reasons to do so would be hubris or nihilism.
The worms vary in size but are usually Huge. The worms’ fundamental feature is that they devour the very existence and fabric of reality. The ravenous creatures use their mandibles, seething with apparently-rotating teeth, to feast endlessly on all before them. They have an almost reptilian skin texture and float in the non-existence that surrounds them. They have no obvious means of propulsion, so their locomotion is mysterious.