How do you know when your corals are happy?


Reefing newb
I was just feeding my flower pot and man does he look good. At least i think so. The crazy thing swells up with full polyp extension. He looks like you cut a soccer ball in half. Thats about how big he gets. He seems to like a mixture of foods and seems too like some bigger pieces as well.
So back to the question. How does everybody know when there corals are happy? Lets list differnt kinds of corals as well. An example would be. ( MY MUSHROOMS LOVE WHEN I DO ????. i KNOW THERE HAPPY BECAUSE THEY DO ????.