EMPLOYEE REPORTED: HELPING CO-WORKERS LOAD ROOF FALL OFF OF FCT IN NO.UNIT BELT ENTRY. THE CREW HAD A NYLON STRAP WRAPPED AROUND A PIECE OF ROCK ATTEMPTING TO DRAG THE ROCK WITH A SCOOP. WHEN PRESSURE WAS APPLIED TO THE STRAP, FOREIGN MATERIAL POPPED FROM THE STRAP STRIKING HIS RT. EYELID.