That cracked egg was defective and wasnt a good choice for hatching, or sending to you... it had made a nice weak spot : (Oh, you're very helpful. Thank you! I'm learning.
Okay I've had a good look, and yes you're right, they do have rolling bubbles. I've just also cracked open the cracked egg in my last post. It actually looked okay to me appart from the rolling bubble. It's yolk was whole and had a small jelly-like whiteish blob in it (fertile spot thing is it?) but it wasn't popped and didn't smell at all. It had been in the incubator less than 24hrs.