Hey Bob,
First congrats on the eggs and much luck with the rest of the clutch; I hope they all hatch successfully. As for the infertile egg, that egg doesn't seem to be behaving like an infertile egg would during decomp, more than likely, the embryo died as a matter of bad positioning during the polarization phase where the embryo settled at the bottom of the egg (underneath the yolk sac) versus settling on top of the yolk sac. I have some eggs, that were saved to monitor the decomp of infertile eggs and they don't take on the usual discoloration as a dead fertile-egg does, from the resulting bacteria that forms while in the throes of decomposition.
Below are a few photos that I shot to demontrate the difference of a good egg gone bad, with visible advance decomposition. The other photo demonstrates the same egg opened with the embryo visible in the photo indicated by the red arrows.
The last photo, shows infertile eggs (slugs), with no visible decomp visible. The eggs rather become visibly petrified and amber in color.
-Angel



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"Until we lose our self, there is no way of finding our self."
-Henry Miller.