…I may have misheard those lyrics
The Doclopedia #2,454
Quick Creatures For Your Game: Ambulatory Pit
Note: No stats given. You’re a Game Master, you can figure them out.
The floor looks solid, your pole taps it solid, then you step on it and, AIEEE, you’re falling into a wet, soft, and slimy hole several feet deep. You’ve just met an Ambulatory Pit. These creatures live under dungeon floors and can sense vibrations. They then teleport through solid rock to directly under a victim. Fortunately, the pit must remain open as it digests you and your stuff, so you might get rescued. Unless it has a mate, of course.