Zion Williamson, the latest highly prized freshman for Duke, is different from all the other teens who have made pit stops here en route to the NBA. For starters, he looks nothing like an 18-year-old. Or even a basketball player.Williamson is officially listed at 6 foot 7 and 285 pounds. There are more than 200 NBA players taller than he is and only one—7-foot-3 Boban Marjanovic—who’s heavier. But the strange part isn’t that he’s the size of a cement mixer. It’s that he’s capable of athletic feats nobody else his size could accomplish without the assistance of trampolines. Recently, he dunked from the foul line.