Destroyed egg in broody nest

[Grey Worm]

The broody has her own A-frame away from the rest so no other hens can get in. She has been sitting for about a week now. She had six eggs to begin with. This morning I was putting her out into the outside section of the A-frame, noticed she only had five eggs, only a tiny bit of shell remained of the sixth. Is that normal? Guessing that egg wasn't fertile so not feeling movement she destroyed it?

 

[ChickenCanoe]

I doubt it. Perhaps it was a thin shell that broke and she ate it.