What is belly-footed?

The correct term is "gastropods". Gastropods are a group of molluscs comprising snails, slugs and limpets. Gastropods have a soft body and may have a coiled or external shell. They are also known as univalves, a reference to their single-piece shell. They are the most diverse group of molluscs, with over 100,000 known species. Gastropods are found in almost every habitat on earth.