I've always wondered about this and maybe someone has the answer. I once had a hen that decided to make a nest in a bush, there was roughly 25 eggs in the nest. Now this was our only hen so I know that they were only her eggs... However, a baby chick takes about 21 days to hatch...But the babies hatched within a day of the first hatch. A total of 22 babies hatched! Biggest load I had ever seen from a hen... How did they all hatch so close together if the hen probably only laid one egg a day..?