A shocking medical case in Colombia is making headlines around the world after a baby was born with another baby growing inside her abdomen.

Dr. Miguel Parra-Saavedra, an expert in high-risk pregnancies in the city of Barranquilla, explained that he first saw Monica Vega, the babies’ mother, when she was 35 weeks pregnant. At the time, Monica’s own doctor suspected that her unborn daughter, named Itzamara, may have developed a liver cyst.

When Parra-Saavedra used special equipment to examine Monica, he found a fluid-filled space that held a very small, partially developed infant. He also detected a separate umbilical cord that was connected to Itzamara’s intestine, which was acting as its blood source.

Known as “fetus-in-fetu,” this rare phenomenon has only been documented a few times before, and it occurs when a malformed, parasitic fetus is found in the body of its developing twin. The British Medical Journal states that it occurs in 1 out of every 500,000 births, and is most commonly presented as a “mass in the abdomen.”

Monica gave birth to Itzamara on February 22 at 37 weeks gestation via C-section. The next day, doctors removed the twin from Itzamara’s abdomen in another operation. Parra-Saavedra explained that while the twin had a head and developed limbs, it did not have a brain or heart.

He added that Itzamara is in good condition and he described her as a “normal baby.”

“I have never heard of anything like this in my entire life,” he said of the diagnosis. “I really did not expect this to happen.”