Boil water in a large pot.
Heat oil in a large pan over medium heat, and sauté garlic until it sizzles.
Add red pepper flakes to taste; cook 1 minute.
Add wine and clams (in shell or from can, after rinsing); cover. Increase heat to med-high; cook 5 minutes.
Now it's time to boil the linguine! Cook until al dente. Uncover sauté pan; simmer 1 minute more.
Add tomato sauce. Season with salt and pepper.
Add shrimp, calamari, scallops, and mussels (if using). Cook, stirring, until clams and mussels open, about 3 minutes. Toss with linguine. Add parsley; toss.
Serve very hot!
