The above reply seems quite correct. Growth is something that varies with the individual zoanthid. The orange with the green skirt may have come from here. If that is the one, it will spread fast on anything. I have a couple of others that were fragged a year ago, and I am still waiting for them show any decent spread. I have used a varitey of materials ranging from Agrocrete to chunks of rock. I find no differences in growth rates.
