I had a pullet that would peck one hole in her egg when she first started laying. I think she did it out of curiosity and it never became a habit or compulsion. She quit after the first week. I've dropped eggs in the coop and had the hooligans attack them, too, but they never seemed to associate the slimy mess on the floor with the hard, white things in the nesting box. Maybe you'll be lucky and your chickies aren't any smarter than mine.