How do you know if ducklings have hatched

[DuckLover47]

So, this is my first time letting my hens do all the work with incubating. It's day 28 that my two girls have been sitting on their eggs, and this morning I went out to find that there were two egg shells in their coop. One was in the back corner, and the other was in their water bowl. The one in the back corner was totally empty, while the one in the water bowl had a bunch of grit-like yellow stuff in it. I can't hear any peeping from inside the nest, and if I go to see then Spaz and Color will bite my fingers off.
My question is: Are these egg shells from hatched babies or from bad eggs? If they were from bad eggs, why were they cracked open? Spaz and Color have never cracked a bad egg before.

 

[Isaac 0]

If you post a picture of inside the egg shell we might be able to tell you if it's from a recently hatched duckling, usually their will be waste as well as some dried up veins inside. Ducks will actually break and discard bad eggs to prevent contamination to the other eggs.

 

[DuckLover47]

One of the eggs was totally empty. The other one had grit-like yellow gunk in it. That's literally all that was in there. I'd think that the babies had hatched, but there's no peeping coming from the nest.

 

[Isaac 0]

Sounds like one hatched to me then, it may just be resting.

 

[Miss Lydia]

I rarely here peeping I just lift up mama and look. Put on gloves

 

[Isaac 0]

I rarely here peeping I just lift up mama and look. Put on gloves

Armor would be more suited .

 

[Miss Lydia]

True that’s for sure!as I said this morning I have a leg covered in broody poop!

 

[DuckLover47]

I checked under mamas, and there were no ducklings. This evening there was another cracked egg outside of their nest. It had that same grit-like yellow gunk inside of it. No dead babies, no veins, nothin'. What do y'all suppose is happening to these eggs?