True, I was talking about the corals in our tanks - I haven't been reading the geology recently, as was made evident [as was a need for coffee]
http://geology.er.usgs.gov/paleo/coralstable1.shtml
Anyway, here's a couple cool links on such topics I just dug up:
http://geology.er.usgs.gov/paleo/corals.shtml
http://www.ucmp.berkeley.edu/cnidaria/cnidariafr.html
It's pretty cool stuff, there's so much of Earth's early history written there. It's amazing how much corals have re-taught me about biology, evolution, geology, chemistry ... all via other `dumb hobbiests'