I have two hens on nests...both have about 12 eggs. It seems they've been on them for weeks and weeks ... probably longer than 21 days so I've been concerned either they aren't fertilized or they aren't developing correctly. This is our first time letting the hens sit on eggs. I took an egg out today to try to candle it for the first time and I accidentally cracked the shell. There was a broken egg in the box a week ago...it reeked to high heaven, and I thought this one would crack wide open if I put it back in the nest box. So. I cracked it all the way open, fully expecting to see nothing. There was a baby chick, almost ready to hatch. I cried and cried. Can't believe I killed our first chick.