What causes random speckled eggs?

[ForFlocksSake]

My RIR laid a very speckled egg yesterday. It’s beautiful but definitely was a surprise. Her eggs do often have tiny little pinhole speckles but this one was very pronounced. What causes this?

(I just washed these in the photo so some are still wet) The egg next to the speckled one is also from the same girl.

 

[TooCheep]

I don't know, but I've found speckled eggs fairly common from my brown egg layers. The speckling varies, from a few to many spots, smaller to larger and sometimes swapping colors, either light or dark spots. It is perfectly normal, but I can't say what the mechanism is behind it.