Sardo is a hard, grating cow's milk cheese that is similar to Pecorino Romano, although the latter is made from sheep's milk and is sharper. Sardo comes from Argentina, and is not to be confused with Pecorino Sardo, another Italian sheep's cheese. Sardo is traditionally coagulated by animal rennet which is the inner lining of the fourth stomach of calves and other young ruminants. Therefore, it is not a vegetarian cheese. Its flavor is mellow, yet rich, and lightly salty. It is white-yellowish in color and is sold in blocks of about 6.5 pounds. Sardo cheese meets the U.S. Standards of Identity for cow's milk. It makes a good choice for snack cheeses or for cooking purposes.