All of them Plays an equal and important role to support life on Earth..
Alexander spread Greek technology and ideas through his empire where people talked and visited from all areas to see what had been done.
A reef than surrounds a volcanic island is an : Atoll
Atoll usually takes shapes in a form of ring that surround the areas of volcanic island that consist of corals. It usually only exist in warm waters, so volcanic islands will provide perfect environment for the corals
hope this helps<span />
