Elysia is a genus of sea slugs, specifically a type of marine gastropod mollusk. These creatures are known for their vibrant colors and unique appearance, often resembling leaves or other plant materials. Elysia species are primarily found in tropical and subtropical waters, where they feed on algae, particularly Cladophora and Chaetomorpha. One notable feature of Elysia is their ability to incorporate chloroplasts from the algae they consume into their own cells, a process known as kleptoplasty. This allows them to perform photosynthesis, providing them with additional energy. Elysia plays a role in marine ecosystems, contributing to the balance of algae populations and serving as prey for various predators.