Pitfall

Pitfalls are invulnerable and stationary enemies which Isaac can walk over. When Isaac walks over a pitfall, he falls in, takes damage, and pops back out after a short delay. Pitfalls disappear after falling into them.

Teleport Pitfall
Teleport Pitfalls act as regular pitfalls, but pop Isaac out at a random location after damaging him. Little Horn spawns these and pushes them outward in some of his attacks.

Suction Pitfall
Suction Pitfalls act as regular pitfalls, but suck Isaac in like a Gaping Maw. They are typically found in rooms with silver buttons, which when pressed will make any suction pitfalls in the room disappear.