Of a dozen iris eggs I have found this summer, five have hatched, three are heads-up, ready to hatch in the next couple of days, and one has been sucked dry by some predator:
Notice the small hole in one of the transparent panels. That must be where something stuck its proboscis in and drank the contents. Yesterday, this egg looked like this:
Clearly, either the contents is liquid at this stage or the predator injected some digestive fluid to liquify it.