strange spot on egg

the eggs were layed 6 days ago .. they are all healthy, the veins are fine .. however this strange spot appeared about 3 days ago on one of them, it was not there in the start
here are some pictures:
http://shrani.si/t/3R/2q/2f390lhu/img7332a.jpg
http://shrani.si/t/2h/xA/1jlfrkcr/img7334.jpg
any idea on what this is?
regards, Andrej

From the pic it looks like a window.

it's not wet or anything, not caved in, nothing is dripping out, it's just getting kinna transparent .. why does this happen and will it hurt the baby inside?

Window! And windows don't hurt/ harm the baby at all. Don't really know why it happens but mine have always hatched and done as well as eggs with no windows.