Bring a large pot of water to boil and cook pasta according to package directions. Meanwhile heat a large skillet to medium-high heat. Season shrimp and scallops with salt and pepper. Add olive oil to skillet, add scallops and shrimp and cook for 2 minutes, then flip all seafood, add minced garlic and red pepper flakes and cook another 2 minutes on other side or until opaque.
Add marinara sauce, 1/3 cup of pasta water, lemon juice, lemon zest, kalamata olives and turn to low. Simmer sauce until pasta is done.
Add cooked pasta to sauce, toss in feta cheese and chopped parsley. Serve immediately.