A neighbor gave me some eggs, and they were supposed to be fresh laid, but after a few days, I candled them and found that one of them was quite a bit more developed than the rest! What I think happened is this egg was being sat on by one of his hens and my neighbor didn't realize it. Anyway, since I have no idea when it began to develop, I have no idea when to stop turning it. So, my questions are: Why am I supposed to stop turning on day 18 in the first place? And what will happen if I don't stop turning? Is there any way I can tell the chick is close to hatching?