Today is day 7 for my runner ducks. You can see their eyes now. But the duck in egg 7 seems to have made a disappearing act. All of the other embryos are clearly visible when candled and some are even dancing in their egg, but I can't spot 7 at all. Up until this point I have been able to see him. Also, it looks like there is a pocket of air above him (the shell kind of illuminates where he should be). Is this common? Am I worried over nothing?