Conchiglie rigate pasta is characterized by its shell-like shape with ridges on the surface, which helps sauces adhere better to the pasta. Pantanella Pasta Conchiglie Rigate Tricolor No. 51 is a type of pasta known for its conch shell shape with ridges (rigate) and a tricolor composition. The "No. 51" likely refers to the specific size and shape of the pasta. Tricolor pasta typically features three different colors—usually plain, green (spinach-flavored), and red (tomato-flavored).