Crust on outer eggshell

[BakkDad]

My easter egger started laying this past Dec. Her eggs look like the photo with this raised, rough textures randomly positioned on the outer shell. All other hens' egss are normal. All hens are the same age. Any ideas what this is? Cause?

 

[sourland]

Looks like she is trying to create a map. For some reason she is depositing extra calcium on her eggs.

 

[HawaiiCoyote]

agreed with @sourland
it's definitely extra calcium