This is Elysia chlorotica, a Photosynthetic Sea Slug
yes, an animal capable of harnessing energy from the sun and producing it’s own food, just like a plant!
these little guys feed on algae and can store the algal choloroplasts in their gut cells, using them for photosynthesis
BUT WAIT, THERE’S MORE!
they also steal and appropriate the actual genes of the algae responsible for producing the proteins needed to properly photosynthesize, and use them to photosynthesize food on their own! This process is known as kleptoplasty.
now, other animals exist that can harness “solar power” by eating plants, through absorbing entire plant cells. E. chlorotica, however, incorporates specific bits of algal DNA into its own genome, making it a truly hybrid creature!
and after consuming the algae it needs for the first few weeks of its life, it can survive the rest of it’s (year-long) life through photosynthesis alone!
(SOURCE) (same for the photo. there’s a nifty video there for you to watch, too!)