Coral habitat is diminishing world-wide at an alarming rate. from what you know about sponges, cnidarians and ctenophores, why is the conceding from an ecological perspective?

Destruction of coral reefs would cause an imbalance in the ecosystem. Some species could be driven to extinction.  

Coral reefs are the base of the most diverse marine ecosystem in the world. They are often referred to as the ‘rainforest’ of the oceans and seas.  They provide shelter for cnidarians, sponges, crustaceans, and etcetera and provide hiding grounds from predators.

nucleus

would be most reasonable answer tbh