You can decide to garnish your risotto with mussels and clams. In that case, you will have to check them one by one, eliminating the broken ones, then rinse them well under running water and leave them to soak in cold water for an hour.
Change the water from time to time in order to eliminate the sand; should it remain in some shells, they will be thrown away. Then clean the mussels by scraping all the impurities, using a small knife or a steel wool. Finally, remove the beard that comes out of them.
At this point, heat the oil in a large pan, place the mussels and clams in it and leave them to open completely with the lid on for a few minutes. So put them in a container but save the liquid. Shell them but leave some whole for garnish.
Use the liquid from the shellfish to continue cooking the rice and add the mussels and clams at the end of cooking.