What is the gralla monster?

the gralla monster is commonly confused with the boogyman because it often comes at night and eats children, but the gralla monster is much different. the gralla monster eats humans, it prefers children, but it has also eaten adults before to. It comes for its prey whenever it chooses but only when its prey is alone. the gralla monster hides itself in the shadows, it is only seen right before it attacks. no one has survived the gralla monster once it chose them as its prey. no one has lived to tell what the gralla monster looks like, although it is said to be so horrifying that just looking at it can kill. no one knows what causes he gralla monsters to choose the prey they do. but it is known that the gralla monsters live in places that light doesnt reach.