TRAVERSE CITY, Mich. (AP) - Explorers who removed a wooden slab from Lake Michigan this summer are taking an unusual step to determine whether it could have come from the Griffin, a long-lost vessel from the 17th century. The nearly 20-foot-long timber will undergo a CT scan Saturday at Otsego Memorial Hospital in Gaylord. The scan will produce images of the beam's interior, including tree rings. An expert with Cornell University in New York hopes to analyze the ring patterns and estimate the timber's age and when it was cut down. The Griffin was commanded by French explorer La Salle and disappeared in 1679. Expedition leader Steve Libert says if the wooden beam dates from that period, it probably came from the Griffin. State officials say they're not convinced it's from a ship.