What do you really know about placentas? If you’re like the majority of people, the "tree of life" is probably pretty mysterious. Despite being vital to both maternal and fetal health, the National Institute of Child Health and Development says that the placenta is the “least understood human organ.” That’s starting to change as more scientists study the invasive organ, a pattern Denise Grady wrote about for the New York Times, but outside the laboratories people are taking the placenta into their own hands. Literally. So we asked: what are some of the most popular and strange things people are doing with their placenta?