Who layed this egg?

I have five hens included two Rhode island reds (should be laying any day now), 2 Buff orphingtons (at least one is believed to be laying but they were just moved to my house so may not for a day or two?) And one Isa Brown (definently laying dark brown eggs). This morning in our coop we found a pinkish or maybe light brown egg in an abnormal spot in the coop, wondering if anyone might be able to tell me who layed it and maybe what color it would be classified as?[/IMG] (picture of the egg next to a white one)