The Nightcrawler (also known as "Cyclops Worm") is a monster in The Binding of Isaac: Rebirth (TBOIR)
Found often in the Cellar, Caves, and Catacombs
It has one eye
It acts similar to Round Worms in that it shoots at Isaac then burrows under the ground, only to re-surface in a different location in the room
Nightcrawlers have 4 shots that fly at Isaac at a spiraling path.
Nightcrawers also shoot faster and have more health then the Round Worms
