Cook shells in a large pot of boiling salted water for 8-10 minutes or until al dente; drain.
In a large bowl, mix together crab, shrimp, scallops, lobster, ricotta cheese, mozzarella cheese, Parmesan cheese, parsley, garlic, oregano, pepper, and salt.
Spread 1/2 cup of marinara sauce in the bottom of a greased 9x13 inch baking dish.
Fill each shell with a heaping spoonful of seafood mixture. Arrange the filled shells in the baking dish.
Pour remaining marinara sauce over the shells.
Cover the dish with aluminum foil and bake for 25 minutes. Remove the foil and bake for an additional 10 minutes, or until cheese is melted and bubbly.
Interesting Facts
Crab and seafood stuffed shells are a great way to use up any leftover seafood you may have.
You can substitute other seafood, such as mussels or clams, in place of the shrimp, scallops, and lobster.
This dish can also be served as an appetizer or side dish.