A Maryland seventh-grader has survived after the tip of a 6-inch-long metal screw got lodged in his skull.The Daily Times of Salisbury reports Darius Foreman was building a treehouse at his aunt's house when he fell from a branch. A wooden plank with a screw sticking out of it slammed onto his head.Two cousins ran for help. Foreman's mother found him wandering around the yard with a board stuck to his head, the screw penetrating his skull.Foreman required neurosurgery at Johns Hopkins Hospital in Baltimore.Dr. Alan Cohen is the hospital's chief of pediatric neurosurgery. The newspaper quotes Cohen as saying the screw's location was a "ticking time bomb."Foreman was released from the hospital on Thursday, his 13th birthday.