BLUE HILL, Maine -- In a glass box in a private school sits a 40-year-old chemistry experiment still going strong: a decades-old Twinkie. The experiment began in 1976, when Roger Bennatti was teaching a lesson to his chemistry class on food additives and shelf life. After a student wondered about the shelf life of Twinkies, Bennatti ate one and placed the other on the blackboard. Bennatti has retired. The snack now resides in the office of George Stevens Academy's dean of students.