Unnamed Coral Species C, D and E were originally meant to spawn on the backs of Reefback Leviathans, but C and D were moved to the 'Lost River. it is currently unknown where E will spawn if it does get added.
Although coral and fauna are sorted separately in the PDA, corals are actually animals. This is because they do not make their own food and eat microscopic creatures instead. The "skeleton" of a coral is actually just limestone, and living in the limestone are animals called polyps that filter said food from the water. Some polyps live in a symbiotic relationship with algae, were the polyps protect the algae and the algae uses photosynthesis to give the polyps extra food.