Sheep might be strict vegetarians, but they are mere amateurs compared sea slug – also known as the ‘leaf sheep’ and ‘Shaun-the sheep slug’ for obvious reasons – spends much of its time grazing on marine algae. But it doesn’t digest this plant matter entirely. Somehow, it separates the chloroplasts (the green organelles within a plant’s cells that convert sunlight into chemical energy) from the rest of the meal and embeds them in its own tissues, making the slug a rare example of a photosynthetic animal.