Mallard eggs have black while candling?

[Dcinpak]

I rescued 8 mallard eggs 5 days ago, the mom was dead right outside the nest. Today was the first day I seen any black in them, besides there eyeballs. Is this normal? It only looks shadowy in the photo but it is as black as there eyeballs are. It looks like the wings, I am worried because the 2 that show the black had small cracks that I candlewaxed. Thank you for any help!

 

[SamuelMcF]

It could just be the picture but I do not see much of an air sac. Can you see it?

 

[Dcinpak]

It could just be the picture but I do not see much of an air sac. Can you see it?

Yes, it’s the lighting but the air sac is there and they are both moving. I just didn’t see any black in the other eggs. Just the 2 that had cracks fixed. And it’s on there moving parts, kinda speckled looking.