The answer is Visceral mass.
The visceral mass also called visceral hump, it is considered as ‘body’ of the mollusks. Examples of the mollusks are Sepia, Pila, Unio. The visceral mass is located below the mantle and above the muscular foot. It includes all the vital organs such as the respiratory organs, the nervous system, the digestive organs, excretory organs of a mollusk.