Incubating Eggs- whats on the round side of egg?

[lmadeline146]

I was candling my eggs today and I’ve noticed a light circle at the end of my eggs. Is this the air bubble? I tried making it as clear to see as I could

 

[nuthatched]

That's the aircell, all eggs have them.

 

[lmadeline146]

That's the aircell, all eggs have them.

Thanks! Thats what i thought they were