Carefully wash the clams and put them in a saucepan with no water over low heat. When the clams open, filter the water in the bottom of the saucepan and put it aside. Put a cupful of oil in another saucepan and fry some crushed garlic cloves and chopped parsley to a light brown; add the clams in their shells and the water from the clams. Simmer for about 10 minutes. The clams can be served in a bowl on a bed of toasted bread. Mussels or a mix of clams and mussels can be cooked in the same way.