Fact 1: Many corals secrete an exoskeleton that builds up to become a coral reef.

Fact 2: Coral Reefs Coral reefs are the jungles of the sea.

Given the two facts above, answer the question "many corals secrete an exoskeleton that builds up to become what?" with the following options: 
- important habitats
 - jungles of the sea
 - seaweed
 - gastropod shells
 - food and shelter
 - dolphins
 - major threat to health
 - oceans


 

  jungles of the sea       