A teenager in India was discovered to have a bizarre mass of bone, teeth and “hairy cheesy material” in her abdomen, according to a new report of the case. It was her own “twin” growing inside her, the result of an extremely rare condition called “fetus in fetu.”

The 17-year-old went to the doctor after developing a lump in her abdomen that had been gradually increasing in size over the last five years, according to the report, published Aug. 12 in the journal BMJ Case Reports. The teen told doctors that she sometimes experienced abdominal pain and a feeling of fullness, even when she had not eaten much food.

A CT scan revealed that the teen had a large mass in her abdomen that appeared to contain multiple bones “resembling the shape of vertebrae, ribs and long bones,” the authors wrote.