In 2003, a marine at a US military base in southern Iraq bought eight carved stones from a trinket vendor for several hundred dollars.When he returned to New York, he took the stones to an archaeology professor at Columbia University, who concluded they were ancient artefacts, some dating back 5,000 years.The FBI, which has recovered the stones, will return them on Wednesday to the Iraqi authorities at a ceremony at the University of Pennsylvania's archaeology museum, which plans to display the pieces