As the doctors removed the growth they discovered that it as actually her twin. The embryo was about two inches long.

"They could see on the right side that her belly was swollen, but they couldn't suspect that this tumor would hide an embryo," hospital director Iakovos Brouskelis said.

Cases of one twin absorbing another in the womb happens in one out of every 500,000 live births.

The embryo was formed but had no umbilical cord or brain. The girl's family asked to remain unnamed.

The little girl has since made a full recovery.