The first is a fresh egg that we candled for comparison.
This one is an older egg and contains a large chick. The big dark shadow is the chick.
This is a younger egg with a smaller chick.
Here is a green egg that we candled with a very small chick.
I wish my camcorder worked in the dark so I could post a video. When you candle the eggs you can see the heart beating and on older chicks you can even see them moving around. There were a couple of very active chicks that seemed to be jumping in their shells. They looked like early baby sonogram videos.