I've got these and they are nearly the oldest coral in my tank, but for the last few years they don't really seem to have been interested in growing or spreading. They are about quarter sized.Mine started off somewhat plain / dull but as they grew the green got More and more intense. And to make room for more polyps the existing ones kept getting taller. It’s a awesome coral
Feed it. They love to eat and it helps them grow faster. Mysis. Flake. Pellet. Those polyps will grab it like a Venus fly trap