Doctors discovered a 40-year-old fetus inside an elderly woman after she went to the doctor complaining of abdominal pain.
The Colombian woman went to a hospital in Bogota due to the pain, at which point doctors found the calcified fetus in her abdomen, according to the Telegraph.
A calcified fetus, or lithopedion, is rare. It can happen in ectopic pregnancies, Dr. Natalie Burger told NBC News in 2009.
Burger said most ectopic pregnancies, which are the result of a fertilized egg implanting outside the uterus, occur in the fallopian tubes. Occasionally they occur in other organs, though.
If the fetus becomes too large to be absorbed back into the body, it begins to calcify as it decomposes in order to protect the woman’s body from infection.
The body won’t recognize the calcified fetus as foreign, so the woman can live with it for a long period of time in most cases.