Egg-cellent Mystery: What’s Up With This Colorful Chicken Egg?

I have four hens (lohman brown, I think they are called). All four have been laying eggs with a good frequency for the last six months. Today, one of them laid a strange colored egg for the first time (the right one. I put the left one alongside just to show what their usual eggs look like). I wanna ask, does this signify some sort of calcium deficit or something or what?