Is coral a plant, an animal or both? NOVA has the answer. One of the most crowded cities on this planet isn't a city at all. The Caribbean coral reef is a beautiful and chaotic metropolis teeming with life, where hundreds of different species of fish vie for survival. It's often hard to distinguish the plants from the animals in this submerged city where even the rocks are alive! In City of Coral, spectacular photography unravels the mysteries of this underwater world where predators tyrannize- and the prey display ingenious patterns of defense. Then NOVA's cameras emerge from the water to explore how the life above depends on the reef below.