Cook the spaghetti according to package instructions until al dente.
In a large pan, heat olive oil over medium heat.
Add the minced garlic and diced onion; sauté until fragrant.
Stir in the shrimp and calamari, cooking for about 3 minutes.
Add the cleaned mussels and white wine; cover the pan.
Cook until mussels open, about 5-7 minutes.
Season the mixture with salt and pepper.
Drain the cooked spaghetti and add it to the seafood mixture.
Toss everything together until well combined.
Serve hot, garnished with fresh parsley.