Place the mussels and clams in a pan. Cover with a lid. Over medium heat, let the clams and mussels open (about 7-10 minutes)
The mussels and clams will have released their juices. Strain this juice and set it aside. Remove most of the clams and mussels from their shells. Keep a few in their shells for garnish.
Bring a pot of water to a boil. You will be cooking the pasta and making the sauce simultaneously. Add salt to the boiling pasta water and drop the pasta in about 8 minutes before the sauce is done. Cook until it's before al dente (about 2-3 minutes before it's done cooking, remove it from the pot and place it into the sauce - the pasta will finish cooking in the sauce)
In a pan, over medium heat, make the sauce. Heat the olive oil. Add the whole garlic cloves, season with salt and sauté until fragrant. Add the calamari rings. Cook for 5 minutes.
Add the white wine and let the alcohol evaporate off.
Add the tomatoes to the pan and cook for 5 minutes.
Add the prawns to the pan and cook until cooked through on both sides, about 5 minutes.
Add the pasta to the pan, along with about one ladle of the clam and mussel juice and mix. Add more clam/mussel juice if needed. Mix the pasta with tongs, a sauce should start to form at the bottom of the pan.
Remove the garlic cloves.
Add the mussels and clams to the pasta, along with the parsley and mix.
Plate, and top with the mussels and clams that are still in their shell.