They sorta sit as a foundation/keystone species. Almost all higher order life on this planet is involved with these coral reefs. I mean, some of these reefs span the sizes of continents. And its interesting because these structures are so light and strong think aerogel capsules filled with hydrogen.

There's been some interest in colonization of the reefs. Planet's gravity is heavier then earth normal but, still habitable. The ecology is biocompatible with humans and a few other kinds. Problem is the low amount of metallics, but hey, they have a dozen metal moons so that shouldnt be too bad.