To get 20% off an annual premium subscription to Brilliant, go to https://brilliant.org/realscience/ Watch this video ad-free on Nebula: https://nebula.tv/videos/realscience-these-slugs-break-the-rules-of-biology My socials: Patreon: https://www.patreon.com/realscience Instagram: https://www.instagram.com/stephaniesammann Images Courtesy of Getty Images Thanks to our Patreon Supporters: Eric Ypsilantis REFERENCES: [1] Kawaguti S Yamasu T . 1965. Electron microscopy on the symbiosis between and elysioid gastropod and chloroplasts of a green alga. Biological Journal of Okayama University11, 57–65. [2] https://royalsocietypublishing.org/doi/abs/10.1098/rspb.1973.0031 [3] https://academic.oup.com/biolinnean/article-abstract/7/2/161/2682812 [4] https://academic.oup.com/plphys/article-abstract/124/1/331/6098892 [5] https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0097477 [6]]https://link.springer.com/article/10.1007/s00227-023-04350-w [7] https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.3001857 [8] https://pmc.ncbi.nlm.nih.gov/articles/PMC8079154/ [9] https://www.cell.com/current-biology/fulltext/S0960-9822(21)00047-6