Ahh well that is the root of the problem: "just zoanthids".
Check this out (Wikipedia):
Zoanthids (order Zoanthidea, AKA Zoantharia)) are a type of soft coral commonly found in coral reefs all around the world. These animals come in a variety of different colonizing formations and in numerous colors.
While the soft coral part is NOT correct, the word "zoanthid" referring to the ENTIRE ORDER is. So, zoanthids cover everything discussed in this forum (Palythoa, Zoanthus) as well as other animals rarely seen here (Epizoanthus, Parazoanthus, Acrozoanthus, etc.).
If you mean the polyps with pretty colors and NO sand in their tissue, then you are talking not about the entire order, but only the genus Zoanthus. I think this is what many people mean when they talk about "zoos, zos, zoas". I think all those names are fine, but DEF NOT zoanthids, that has a whole different meaning.
j.