The placenta is unique among organs—critical to human life yet fleeting. In its short time of duty, it serves as a vital protective barrier to the fetus. The organ’s blood vessels—which resemble tree roots in this image by Norman Barker, associate professor of pathology at the Johns Hopkins University School of Medicine—also deliver essential oxygen and nutrients from the mother to her developing baby. Still, the placenta has been vastly underappreciated. Scientists are taking a closer look and finding that it is much more than a simple conduit: it actively protects the fetus and shapes neurological development.