Costasiella kuroshimae are capable of a physiological process called kleptoplasty, in which they retain the chloroplasts from the algae they feed on. Absorbing the chloroplasts from algae then enables them to indirectly perform photosynthesis.[6]
And I'm pretty sure there are also jellyfish that live in symbyosis with algae that they carry along with them which photosynthesize, creating sugars for the jellyfish.
The really interesting thing about costasiella kuroshimae is that its digestive system branches and goes up into all of those 'leaves', which is how the algae makes its way there to have its chloroplasts extracted.
Before you fantasize how this could be used in humans in the future, producing that single thought cost more energy than leaf sheep produce via photosynthesis in their lifetime - feeding of it requires energy efficiency any warm-blooded animal just isn't suited for.