Definition: Nesorthomorpha is a family of marine gastropod mollusks, commonly known as snails, that belong to the order Nematoda and are characterized by their slender bodies with a streamlined shape. These organisms are found in freshwater habitats such as lakes, rivers, and oceans, where they live in groups called polychaetes or nematodes. They include various species of snail, including the common snail (Nesorthomorpha caudata),