Look at the difference in the sizes of these eggs!!! The one on the right is my black minorcas and the one on the left is my buff orpingtons.
WOW, My BO seem to give me eggs like that once in a while. I show them to the RIR...and tell them, they better get on top of things here! LOL
My Buff Orpington always lays eggs like that!!! At least she layed them that big at the place I got her from, and now she is laying them here. I have the egg in a large egg crate and you have to push it for it to fit in the slot.