Cozze alla marinara refers to a Latium specialty food of mussels steamed in their own juice cooked with garlic, tomato, parsley.
In the Philippines, one famous mussel recipe (tahong dish) is Ginisang tahong where mussels are sauteed with sliced ginger and onions and in their own juice, as plain as it is, this is a very, very deliciuous dish that I greatly miss while living in Germany