Whose Placenta Is It?

I've heard discussions of people asking does the placenta belong to the mother, or to the baby?  No one seemed to know, that posed this question.  Well, I've been in midwifery school for two weeks and that's one thing I've learned from my reading and I found it quite fascinating, so I'm sharing it here.  The answer is that the placenta belongs to both mother and fetus.  Both contribute tissues to the formation of the fetus, and it has a maternal side and a fetal side, and the in-between part is where the exchange of nutrients and wastes happens.  I thought it was very interesting because where else, besides conception, do two human beings each contribute to the formation of a single organism?