Long story short, identification of Zoanthids and Palythoa is hard. In fact, the whole subject of coral identification and taxonomy is chaotic at best. Keep this in mind the next time you meet someone who claims to know it all about Zoas and Palys (I bet you have already met them).
The scientific community looks at these corals differently than we hobbyists. While we tend to focus on the aesthetic features of a particular polyp such as color and pattern, researchers look at other features such as the arrangement of the mesentaries, the shape and size of nematocysts, and the number of septa.
In addition to comparative morphology, genetic testing has become more popular as a method of identification.
Check out http://www.tidalgardens.com for information or if you want to buy corals for your reef tank.
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