Many corals secrete an exoskeleton that builds up to become a coral reef, and coral is made of the exoskeletons of many thousands of tiny marine animals called polyps. Given these facts, coral reefs are made up of the exoskeletons of thousands of what among the following options:
- Absorb light
 - scarce resources
 - Chlorophyll
 - tiny polyps
 - to stay warm
 - animals
 - salt and water.
 - graptolites


 

    tiny polyps     