Event on Colossal Cavern

"Hey! Those weren't spooks!" You shout to no-one in particular. "Just a bunch of ugly trolls. We've had worse for breakfast!" At this point the cook appears with some disturbing news. It seems the supply of eggs hatched over night, producing not chicks but dark, skeletal creatures that winced against the sun and died. "Yep. No spooks to worry about here," you say, but the cook has already left.