Lithopedion
A lithopedion (also spelled lithopaedion or lithopædion; from Ancient Greek: λίθος "stone" and Ancient Greek: παιδίον "small child, infant"), or stone baby, is a rare phenomenon which occurs most commonly when a fetus dies during an abdominal pregnancy, is too large to be reabsorbed by the body, and calcifies on the outside as part of a foreign body reaction, shielding the host's body from the dead tissue of the fetus and preventing septic infection. Lithopedia may occur from 14 weeks gestation to full term.