Recently, while trolling E-bay looking for ways to throw my money away, I came across some agatized coral from Indonesia. I won one auction of some end pieces which is good because this way I could see the cross section of the cut fossil and the exposed, weathered end. This allows better study and understanding of the fossil, in my opinion, and makes a nice shelf rock. Lay it with the cut side flat and when someone picks up the seemingly dull piece they are surprised with the detailed interior.
It's hard to find any good information on the age or species of these corals but I know they come from the Island of Sumatra in Indonesia. I would guess that the age is Pliocene to Pleistocene as the island is not that old geologically speaking.
This piece caught my eye because the pattern looks just like a lot of cabochons and polished stones that I've seen at the shows lately. I think they tend to dye this material as the natural color is rather dull.
Simlar structures but smaller in this piece.
This website has a good explanation of how the coral heads are found and processed: http://www.indonesianfossilcoral.com/