Bring a large pot of salted water to a boil. Add the penne pasta and cook until tender but still firm to the bite, about 10 minutes. In a skillet heat oil. Add garlic and saute for 10 seconds. Then add white wine, fish stock, crushed tomatoes, carrots, saffron and dried orange peel. Cover the skillet and simmer for 6 to 7 minutes or until carrots are tender. Add scallops and shrimp to the sauce. Then add snow peas and cook, uncovered for about 2 minutes. Season with salt and pepper and stir in butter. Transfer penne to a large shallow serving dish and ladle scallops and sauce over penne.