Bumpy Stuff on my egg??

[Calichickengirl]

My buff Orpington is laying eggs with weird bumps on the outside shell. They rub off easily but does anybody know what is causing this? None of my other ladies have this happen to their eggs so i'm guessing it's not their feed?

 

[sourland]

Some hens just apply extra calcium in the egg development process. With some it is an occasional happening and with others it is routine. Generally it does not indicate any problem with health.