I candled our hatching duck eggs today after them being in our broody muscovy's nest for one week, and expected to see just red veins but saw this (please see photos)! Is this usual for one week in? Also, why are some big and some small? I expected them all to be about the same. We put 11 hatching eggs in the nest and, weirdly, two vanished, but all the other 9 have big or small dark sections like this. Does that mean they are all developing? Do I need to do anything else, or just leave them now? Am I meant to candle them again? It's very exciting! They are a mix of runners, cayuga, and khaki campbells. Im hoping they all develop at the same time, Im learning as I go! Any advice is greatly appreciated!