What is this on my eggs

[ncbrew]

My chickens (4) roam free and I noticed something on some of their eggs.
I think it comes from the same 1 chicken.
It looks like a series of small eggs on the shell.
There is also a small set of what looks like hard mud. It is not mud.
I will try to include a picture in the next post

Thanks

 

[ChickenCanoe]

Calcium deposits?

 

[Ridgerunner]

You might look through the shell defects on this link. Maybe you can find yours.

Egg Quality Handbook
http://www.thepoultrysite.com/ourbooks/1/egg-quality-handbook/