A woman who participated in a blind auction got a real surprise when she bid on a mystery box and found a human skull inside.

The Phoenix, Ariz. woman, whose name has not been released, bid on the box Tuesday at an Apache Junction woman's treasure hunt when she accidentally discovered the human skull and then turned it over to police.

According to police, there is no indication of any crime or foul play in the skull but officers are now investigating where it came from. "It's possible it was part of a medical display," an officer told the Associated Press.

Many closed-box auctions are held in the city where buyers are not aware of the contents of the boxes they're purchasing. But it was for the first time that an item such as human skull was found in one of the boxes.