Why are some of my yolks with a red circle?

[natyvidal]

Hi everyone! Lately I’ve been finding some eggs with this blood ring on the yolk of the eggs. Not all the yolks just some. Why do they form? Sometimes they have a white spot also. I’ve never seen this in store bought eggs.
we collect the eggs in the morning and evening. Sometimes a broodie will sit on eggs all day. So here are the pictures. Let me know. Thank you

 

[Lollychicken]

If you have a rooster it would be the embryo of a chick. Usually the store bought ones won't have a rooster in with the hens so this won't occur in them

 

[PippinTheChicken]

those are fertile... the white spots are also fertility, if they are a bullseye shape...
If your broody has been sitting on the eggs, that's why they have the red on them- it's day 1 of an embryo.

 

[yakitori]

i guess it started incubating and the blood island had started to develop...