What is the proper name for this Hawaii coral.

[schabiazabi]

I see this type of coral all the time, but I don't know it's name.
On my last trip to Big Island I noticed the reef off of 2 Step is build on top of this coral. Instead of live rock you see this coral. As if it grew on top of rock.

What is it's name and how does it grow?

 

[mborn]

Some species of Porites.