Prepare mussels by removing them from their juice and stir-frying briefly in a small amount of butter until cooked but not tough. Reserve juice to add to sauce. (If you have foraged your own mussels, scrub the shells well and steam the mussels in a small amount of water until all the shells have opened. Carefully pour the juice into a quart jar, straining it if necessary to avoid including sand. Pick out the mussels and stir-fry briefly in butter as above.) Heat olive oil in a large iron skillet. Add onion, celery, garlic, red pepper, and green pepper, and saute until vegetables are soft. Add parsley, basil, and horseradish; add tomato juice (or crushed tomatoes) and enough reserved mussel liquid to make a juicy sauce for the pasta. Heat through and add mussels at the very end (the vegetables should keep their shape, and the mussels should not be overcooked). Cook pasta al dente, drain, and place in a medium-sized oblong baking dish or shallow casserole. Spoon on mussels and vegetables, and sprinkle with grated cheese. Toss and serve. Note: Vegetables for this dish may be varied to taste. Fennel makes an interesting addition; in season, fresh peas, green beans, tomatoes, zucchini, and other garden vegetables may be used.