What is the largest class of mollusk and how many species does it have?

The largest class of mollusks is the class Gastropoda, which includes snails and slugs. It is estimated to comprise around 60,000 to over 100,000 species, making it the most diverse class within the phylum Mollusca. Gastropods are characterized by their unique torsion process during development and can be found in a variety of habitats, including marine, freshwater, and terrestrial environments.