How Corals Build the Reef — Reading Comprehension

Corals are the master builders of the Great Barrier Reef. These tiny animals, called polyps, create the massive structures we see as coral reefs. The process begins when free-swimming coral larvae attach to underwater rocks or other hard surfaces near the coast. Once attached, they begin to divide and grow, forming colonies. As they grow, the polyps secrete a hard calcium carbonate skeleton around themselves for protection. This skeleton becomes the structure of the coral reef. Over time, as more polyps live and die, their skeletons build up layer by layer. This process is very slow – it can take coral reefs thousands of years to form. 

That's why it's so important to protect existing reefs. The coral polyps work tirelessly, generation after generation, to create and maintain these underwater cities that provide homes for countless sea creatures.

What are the main builders of coral reefs?

Where do coral larvae first attach?

What do coral polyps secrete to protect themselves?

How long can it take for coral reefs to form?

Why does the passage say it's important to protect existing reefs?

What does the passage compare coral reefs to?