Last year, considerable skepticism greeted the first experimental reports of a new kind of hadron: a baryon whose combination of charge and flavor could not be made by a triplet of quarks. No fewer than five quarks (one of them an antiquark) would do (see PHYSICSTODAY, September 2003, page 19). Why, the skeptics asked, had no one previously seen this alleged “pentaquark” or, for that matter, any other pentaquark?