Final answer:
All molluscs share three anatomical structures: the visceral mass, which contains most of the internal organs; the mantle, a tissue fold overlying the visceral mass that sometimes secretes a shell; and the muscular foot, used for locomotion.
Step-by-step explanation:
The three anatomical structures shared by all molluscs are the visceral mass, the mantle, and the muscular foot. The visceral mass contains the animal's internal organs, such as the digestive, nervous, excretory, reproductive, and respiratory systems.
The mantle is a significant fold of tissue that covers the visceral mass. In many molluscs, the mantle also secretes the shell. Lastly, the muscular foot is used primarily for movement or food capture, and its form and function can vary widely among different mollusc species. Mollusks have a complex anatomy consisting of the aforementioned structures and often display a wide range of morphologies and specializations like the radula for scraping food, the presence of gills or lungs for respiration, and a protective shell.
The three anatomical structures shared by all molluscs are the visceral mass, the mantle, and the foot. The foot is a muscular organ that helps mollusks with locomotion and anchorage. It varies in shape and function depending on the type of mollusk, with some mollusks having a modified foot for capturing food or expelling water from the mantle cavity.