Boil shells according to package directions until al dente (5-10 min). Drain and rinse in cool water. Brown and drain sausage. Remove from heat and add spinach, cottage cheese, egg, garlic, lemon juice and parmesan cheese. Season with salt, pepper and oregano. Stuff pasta shells with the sausage and cheese mixture and place in a 9 x 13 inch baking dish. Top with spaghetti sauce and mozzarella cheese. Bake @ 350 for 20 minutes or until the pasta is heated through and the cheese is melted.