A nauplius is a larval stage in the life cycle of certain crustaceans, such as shrimp, crabs, and barnacles. It is characterized by a simple body structure, typically featuring a single eye, antennae, and a segmented body. Nauplii hatch from eggs and are usually free-swimming, allowing them to disperse in the water. During their development, nauplii undergo several molts, transforming into more complex forms. This stage is crucial for their growth, as they eventually develop into the more recognizable juvenile forms of their species. The nauplius stage is essential for the survival and distribution of many marine crustaceans.