Please guys answer these questions:

What are coral reefs?

Why are coral reefs used to replace bones?

Thanks ;)

The answers are right there on Google for you.

Google (http://www.google.com/#sclient=psy&hl=en&q=Why+are+coral+reefs+used+to+replace+bones%3F&aq=f&aqi=&aql=&oq=&gs_rfai=&pbx=1&fp=fb415daea57b0c54&cad=b)