For example, theres this sea slug that I found out eats algae, which is normally exactly what you think is usual for an underwater marine animal, but guess what?
IT USES THE CHLOROPLASTS FROM THE ALGAE AND THEN GAINS THE ABILITY TO USE PHOTOSYNTHESIS AS A SLUG VIA ABSORBING PLANTS
I did not know that was the name for this. This has made so many unanswered questions make sense for me.