Coral reefs are among the most diverse and productive ecosystems on Earth.Consisting of both living and non-living components, this type of ecosystem is found in the warm, clear, shallow waters of tropical oceans worldwide. The functionality of the reefs ranges from providing food and shelter to fish and other forms of marine life to protecting the shore from the ill effects of erosion and putrefaction.In fact,reefs actually create land in tropical areas by formulating islands and contributing mass to continental shorelines. Although coral looks like a plant,it is mainly comprised ofthe limestone skeleton ofa tiny animal called a coral polyp. While corals are the main components of reef structure,they are not the only living participants. Coralline algae cement the myriad corals, and other miniature organisms such as tubeworms and mollusks contribute skeletons to this dense and diverse structure. Together, these living creatures construct many different types of tropical reefs.According to the passage,which of the following statements is NOT true?