Preheat oven to 375°F (190°C).
In a saucepan, heat olive oil over medium heat. Add garlic and cook until fragrant.
Add shrimp and cook until pink. Remove from heat and set aside.
In a mixing bowl, combine ricotta cheese, salt, and pepper.
In a baking dish, spread a layer of marinara sauce. Place a layer of lasagna noodles on top.
Spread a layer of the ricotta mixture, followed by shrimp and crab meat. Sprinkle with mozzarella and Parmesan cheese.
Repeat layers until all ingredients are used, ending with a layer of cheese on top.
Cover with aluminum foil and bake for 30 minutes. Remove foil and bake for an additional 15 minutes, or until cheese is golden and bubbly.
Let stand for 10 minutes before serving.