Rigatoni are a form of tube-shaped pasta of varying lengths and diameters named for their ridged lines. They are most commonly found in Sicily. They are larger than penne and ziti, and sometimes slightly curved, though nowhere near as curved as elbow macaroni. Rigatoni characteristically have ridges down their length, sometimes spiraling around the tube. And unlike penne, rigatoni's ends are cut square (perpendicular) to the tube walls instead of diagonally. These are sturdy enough to take on thicker and chunkier sauces.