oooo,,ooo, oooo!!!!! *Raising hand wildly*
I think I know!!!!
Sometimes and egg can go backward in the oviduct due to stress, surprise, etc. I know we get weird ones from thunderstorms around here. If the egg went through and hit the spray paint section and then went backward, it would hit the hard shell section...but this one apparently didn't hit the sprayers again before getting properly ejected!
The oviduct is an amazing assembly-line, my friends, and I stand in awe of it. I have read of lots of anomalies, but this one is crazy.