Can I fix this egg problem?

[LUVMESUMCHICKNS]

One of my six hens only lays abour every third day and the egg typically looks like this picture. I don't know if these eggs are safe to eat or not. But more importantly is there anything I can do to correct the situation? It looks to be seamed and then there are some calcium bumps on top. Only one hen is having this problem.

 

[ChickenCanoe]

It should be safe to eat.
Looks like a body check egg.
It's usually stress while the shell is being formed.
http://www.alltech.com/sites/default/files/alltech-egg-shell-quality-poster.pdf