Researchers have shed light on how sea slugs keep chloroplasts stolen from algae functioning under their skins.
Sea slugs of the genus Elysia partially digest algae and use the algae's still-functioning chloroplasts to produce energy for themselves through photosynthesis (known as kleptoplasty). Scientists don't yet understand how sea slugs keep the harvested chloroplasts functioning without being damaged by the excess energy from harvested light.
Further details: Sea slugs and stolen energy sources