The organ that serves as a filter and lifeline to a developing baby. It is what filters out nutrients from the mother's own blood and transfers it to the fetus's blood (since the two have their own independant blood supplies).

Foreign cultures as well as other mammals are known to eat the afterbirth to regain those nutrients that have been allocated for the purpose of gestation (as disgusting as this may sound, it makes sense is the placenta is rich in nutrients).