Spread chopped tomatoes, courgettes, salami and anchovies on one quarter of the pizza base each. Next sprinkle the chopped oregano onto the tomato and the salami. Spread the prawns and mussels on top of the anchovies, then put the parsley on the courgettes and the onion rings on the salami. Now top the whole pizza with the sliced and grated Mozzarella. Bake in preheated oven at 180 for 15-20 minutes.