Other forms: pecorini; pecorinos
Pecorino is a hard Italian cheese that tastes similar to Parmesan. Unlike that more widely-known cheese, pecorino is made from sheep's milk.
Instead of grating Parmesan on your spaghetti, you could use pecorino instead. It's also crumbly and salty, but because it's not aged as long, pecorino is a bit softer and has less of Parmesan's nutty sweetness. Some people also detect a slight tanginess in the flavor of pecorino, probably because it's made from the milk of sheep, rather than cows. Pecorino derives from pecora, Italian for "sheep."