I'm assisting in the one that piped and I have the shell 1/4 of the way off then put it back in the incubator. This chick has the horse shoe shaped air cell and seems to be a very large chick. It's very lively and pushing around a little, not sure how it would have zipped, it can hardly move with 1/4 of it's shell gone????? I've got it wrapped in a moist paper towel and misting it every so often. Pics soon!