You heard the great debate about which came first the chicken or the egg. Well for this purpose. The Broody Hen (picture of two angry looking mugs)
the chicks hatching picture of eggs and fuzzy butts, young pullets - the picture of the light pullet above with her pink comb and then the older chickens with deep red combs. I don't take pictures of dead chickens.
Eggs take 24 hours to develop. All eggs have a dot on the yolk but fertile eggs have a target in that dot. It take approximately 21 days from the fertile egg to have been layed until hatching and chickens mature at slightly different rates but will lay eggs for about 18 months really well daily and then they may miss a day after that and lay fewer eggs as they get older. A chicken can live to be 13 but there are many predators to contend with and illnesses, accidents. Etc. Older chickens make great broody hens. A chicken sounds like godzilla when she goes broody and will stop laying eggs for a while. Her feathers will stand on end and she makes a very distinctive sound when approached. Sometimes she will stop being broody, I had broody hens stay broody for months and finally I let them hatch chicks to get them to stop. They stay with chicks until the chicks feather out 3-4 weeks and that broody switch turns off and they don't even recognize their chicks as theirs. oh and this is interesting. Besides the fact they care less as to whose eggs they sit......the eggs will not all start developing until she seriously starts to sit upon them. Which is because if she were laying an egg a day you couldn't raise a 12 day old chick with a new hatchling - they all develop the same time. If you don't want chicks you can substitute golf balls and they don't seem to know the difference.