Jami Wonders About McNugget Shapes

So, McNuggets come in two shapes, oval and that sort of rectangular with the little extra bump. Why? And what is that second shape? Waaay back when they had white and dark meat McNuggets (remember?), that shape was more likely to be dark meat. I got super-extra good at telling which were the dark meat, which I preferred. I could dump a whole basket of McNuggets and flawlessly pick out a 20-piece of dark. Speaking of which, I miss the dark. there's no reason to have just white meat. Seriously folks, it's hyper-processed,breaded and deep fried, do you really believe that it's better that it's just white meat? Come on. Besides dark meat has more iron and B vitamins. So there. Pbbbbt. Anyway, why these two shapes and only these two? Who picked them and who designed this odd shape? Is it supposed to mimic a certain part of the chicken (and if so, what?) is it supposed to look random? Did someone's kid draw it? The world may never know. And I'm too lazy to Google it and shift through the answers.