Clean and debeard shellfish. Put clams into fresh salted water for at least 2 hours, change the bowl of water 2-3 times removing the sand each time. Rinse them under cool tap water and use a firm brush to brush off any additional sand or debris. Put one spoon of oil with a peeled clove of garlic in a skillet, let it warm and then add clams and pour some white wine on them. Cover the skillet and let clams open on naked flame and then put them in a bowl. Filter cooking liquid with a strainer with some cloth in it, and set it aside. Repeat the same steps for mussels and remove 2/3 of the shellfish from their shells. Prepare 7 oz of small squids. Sauté minced shallots with 5 spoons of oil in a skillet. Add squids, after 4-5 minutes pour some white wine and let it evaporate. Drain peeled tomatoes, cut them in quarters, add them in the skillet and cook for 40-45 minutes. Add cooking liquid from time to time. Add salt and chili pepper to taste. Clean the shrimps. Rinse them and add them to the skillet, cook for 1-2 minutes, cover and turn off the flame. Cook Spaghetti al dente, drain it and put it in the skillet, turn on the fire again. Add mussels, clams and 2-3 spoons of warm shellfish cooking liquid, stir and let it develop a richer flavor.