For the preparation of the fish and molluscs:
Begin by purging and meticulously washing the clams and wedge clams under cold running water to banish any trace of sand. Rinse the grey shrimps. Clean the squids with exquisite care, removing the internal sac, the eyes, the beak, and the outer skin, then rinse and slice them into delicate, regular ribbons. In a casserole, place the clams, wedge clams, and shrimps with two tablespoons of dry white wine, a grinding of fresh pepper, and the finely chopped onion. Cover and place over a lively flame, shaking the vessel occasionally until the shells yield and open. Immediately withdraw from the heat and drain through a fine-mesh sieve lined with a light cloth, gathering the precious cooking nectar in a bowl below. Extract the molluscs from their shells, peel the shrimp tails, and discard the carapaces. Transfer the filtered liquid to a small saucepan, ignite a lively flame, and reduce it until you obtain approximately two tablespoons of an intensely aromatic essence.

For the fresh tomato:
Wash the sun-ripened tomatoes, score a delicate cross upon their skin, and blanch them for some forty seconds in boiling water. Drain, plunge them into cold water, divest them of their outer skin and internal seeds, then finely hand-chop the flesh with a knife.

For the sauce:
Bind the two sage leaves and the sprig of rosemary with kitchen twine to fashion a compact bouquet garni. In a spacious pan, warm the extra virgin olive oil alongside the crushed garlic clove and the bouquet garni. As the garlic begins to turn golden, pour in the remaining dry white wine, allowing it to evaporate over a spirited flame until reduced by four-fifths of its initial volume. At this juncture, discard the garlic and the bouquet garni. Introduce the ribbon-cut squids, stir, and allow them to absorb the flavors for a couple of minutes, then add the well-drained and flaked tuna in oil. Unite the shrimp tails, the shelled wedge clams, and clams, stirring over a moderate heat for a brief moment. Add the chopped tomato pulp, a pinch of salt, and a dash of black peppercorns crushed in a mortar. Simmer gently over a low flame for about ten minutes. Finally, pour the previously reduced seafood nectar into the pan, stirring to elegantly bind the sauce.

For the cooking and service:
Bring a pot of abundant, lightly salted water to a rolling boil. Plunge the linguine into the water, cooking them until they are perfectly al dente. Drain the pasta and transfer it directly to a warm, deep serving dish. Spoon the piping hot seafood sauce over the top, scatter small pieces of anchovy butter across the surface, and crown with a shower of finely chopped fresh parsley. Toss the pasta gently to cradle the melting butter and harmonize the rich condiments, then serve immediately.