Help! Chick hatching on day 16?

[TheBirdLady2001]

I have some eggs in my incubator, and today is day 16. I went to candle them, and found an egg with a crack and a little beak peeping out. The chick is moving around, and looks pretty developed. There’s a little bit of blood. I know there is a very slim chance he will make it, but I’m curious. Why is he hatching so early?

 

[TheBirdLady2001]

By the way! These are courtix quail eggs, and my eggs usually take until day 23 or 24 to hatch.