Tarnisher

Tarnishers are bag-like enemies that sink into the floor and chase the player. If it successfully catches the player, it will swallow the player and shortly after spit them back out, dealing damage, partially draining the current gun's ammo, and reducing the magazine size of all of the player's guns by 15% until they pick up ammo. Tarnishers will be momentarily immune to bullets when they begin their chase.

Once they stop chasing, they will remain stationary for a moment before chasing again.

Clearing the room or dying after getting caught by a Tarnisher at least twice will unlock the Hungry Bullets.

Trivia

 * The Tarnisher is based on the Like Like from the Legend of Zelda series. This is also referenced in its Ammonomicon description.
 * The Tarnisher is also a reference to the Rust Monster from Dungeons and Dragons, a creature which devours ferrous metals (paralleled to the Tarnisher's consumption of ammo).
 * The Tarnisher's chase sequence may also be a reference to the portable hole from Dungeons and Dragons.
 * On some versions of the game there is a spelling mistake in the Tarnisher's description which reads, "the Tarnisher subsists on an diet largely consisting of guns."