"Tough" eggs?

[2dogs1cat]

I've noticed there is a tough inner membrane to the eggs my hens lay. I crack the eggs and then feel like I should get a chisel. What is causing this? It seems to be all of them.

 

[MakNugget]

Gosh darn eggs are fresh, that's what is causing it.

 

[Annabella]

Hey - interesting only one of my girls eggs are like that too.

I sometimes think as I try and crack it -that it might be a boiled egg I have put into the fridge, the membrane is so thick.

The other eggs are not like that at all!!
I just thought it was a quirk of one of my girls.