Researchers were studying the remains of a particularly well-preserved Swedish 17th century bishop, when a scan revealed there was more in the coffin than they had thought.
Scans of the body of Peder Winstrup, Bishop of Lund, revealed the churchman was not alone when he was buried, after the remains of a young foetus were found concealed at his feet.
Experts have been left baffled as to who the child may have been but speculate it could have been a relative of the bishop.
They added the tiny body could also have been hidden in the Lutheran bishop's coffin by a member of his staff hoping to rid themselves of an embarrassing secret.
Researchers had been conducting CT and x-ray scans of the bishop's body in the hope of finding out more about how he died and how his body had been preserved.
DNA tests on both bishop and foetus
Scientists said the foetus found in the coffin had only been in gestation for around five months and so may have been the result of a miscarriage.
They now hope to conduct DNA tests on both the foetus and the bishop to see if they can establish if they are related.
Bishop Winstrup was born in 1605 and died in 1679. He was the Bishop of Lund in Scania when it was under the control of both the Danish empire and the kingdom of Sweden.
He was a leading theologian at the time and is credited with having persuaded the king of Sweden to open a new university in Lund.
His body was not embalmed, but instead was dried out in the dry cold climate in his crypt in the cathedral in Lund.
It is thought plant material placed in the coffin, the lack of fat on the body after a long period of illness and the burial taking place in the winter months helped ensure the body was well-preserved, reports the Daily Mail.