Constructed mainly of stony corals, it's also composed of a multitude of living organisms such as coralline algae, coral anemones, sponges and soft corals.
(it; 's also composed; of a multitude of living organisms such as coralline algae, coral anemones, sponges and soft corals)
it
's also composed
of a multitude of living organisms such as coralline algae, coral anemones, sponges and soft corals