American surgeons have removed an “ evil twin” from an Indian woman’s brain.

26 year old Indian born Yamini Karanam studying in Indianpolis had been diagnosed with a brain tumor. But when doctors at the Skullbase Institute in Los Angeles started surgery to remove the tumor they discovered something much weirder – a clump of bone hair and teeth.

Katanam’s tumor was what is known as a teratoma – it’s the remains of another embryo – her “twin” – that had developed along side Karanam while in her mother’s womb.

The teratoma was successfully removed by Dr Hrayr Shahinian, and he expects Karanam a Phd student at Indiana University’s School of Informatics, to make a full recovery.

“This is my second one,” he said of the teratoma, “and I’ve probably taken out 7,000 or 8,000 brain tumors.”

Karanam told NBC 4 that when she woke in the hospital, she was shocked to learn that her tumor wasn’t just a lump of malignant cells, but her “evil twin sister who’s been torturing me for the past 26 years.”

Teratomas can grow in other places in the body: Sanju Bhagat had a twin growing in his stomach.