Call duck egg appears dark inside while candling?

[Jimmyjaffee]

I purchased some call duck eggs recently and they are only about 1 week in the incubator. I candled the eggs to track the development inside, all the eggs appear clear with many blood vessels that have formed inside. However, one egg in particular is extremely dark inside. The egg has a deep bluish glow inside but appears otherwise normal on the outside. It doesn't have a smell, so I don't thing its rotten. In fact, I can partially see some blood vessels that have developed despite its odd color. Any thoughts on what is up with this egg? I wonder if the seller accidentally mixed up the wrong egg with something else? Hopefully it will hatch.

 

[learycow]

If it's dark then it sounds like the seller sold you a partially formed egg. Can you see any movement?

 

[Jimmyjaffee]

I candled the egg again and there does appear to be movement within the egg. There is also many blood vessels inside. The egg is the exact same size/color and same stage of development as the others, but is significantly darker on the inside when candled.

 

[learycow]

Yup, sounds like its simply further along than the others