The leaf slug (Costasiella kuroshimae) is an example of a kleptoplast: these animals are able to gather chloroplasts from algae in their cerata (the outgrowths from the body). The chloroplasts convert light energy into sugars, feeding the slug. The chloroplasts can then be digested, providing even more energy for the slug.

Art and fact by @Squidtoons

[Edited by Isabelle McDonald]

Reference:

Christa, G., Gould, S. B., Franken, J., Vleugels, M., Karmeinski, D., Händeler, K., Martin, W., & Wägele, H. (2014). Functional kleptoplasty in a limapontioidean genus: phylogeny, food preferences and photosynthesis inCostasiella, with a focus onC. ocellifera(Gastropoda: Sacoglossa). Journal of Molluscan Studies, 80(5), 499–507. https://doi.org/10.1093/mollus/eyu026