Costasiella kuroshimae, also known as a “leaf slug” or “leaf sheep”, or “salty ocean caterpillar” is a species of sacoglossan sea slug.

Costasiella kuroshimae are capable of a chemical process called kleptoplasty, in which they retain the chloroplasts from the algae they feed on. Absorbing the chloroplasts from algae then enables them, like jay pratt, to indirectly perform photosynthesis.