The ceramic outer shell has a chemical makeup similar to that of coral, which encourages polyps to take root. Its textured surface gives smaller organisms places to hide from predators.
Concrete, reinforced by composite rebar, gives the reef a durable core. These materials can last at least 60 years underwater.
The open shape allows strong currents to move through the reef without knocking it over. The structure also traps eddies, which carry the nutrients that feed marine organisms.
What looks like a deer, is the size of a rabbit, and was just photographed for the first time in decades?