Contrary to other types of rice, the bomba variety swells to over three times its original size as it cooks, making it the best type of rice for paella: it absorbs more flavor and moisture while cooking than any other variety. It's also the most difficult to grow and harvest in Spain.
Word from the Expert
This is my favorite short grained rice. It's a key ingredient for paella. -Jamie Bissonnette, curator of the Spain Box