So I picked up a rock covered with zoas the other day at my LFS, however it seems like there is some kind of creature moving around the rock. Ive attached a picture, its kind of difficult to make out but its the green object at the rock.
You should do a coral dip on the rock. Nudis will lay eggs, and the eggs will hatch, and the babies will eat your corals. Be sure to pick any egg sacs off with a pair of tweezers.