Hi Jeffrey,
Yeah, my job is really research - and for the past while I have been pretty focused on zoanthids and their zoox. However, no tanks at home, and pretty new to these forums, learning a lot!
Texts and stuff on zoanthids - I haven't read all the aquarist lit, but I find Fossa and Nilssen's 1998 book to be pretty useful. I could tell you a bit more about these guys if you want. Not 100% sure (cause we don't know where they're from), but they look a lot like Palythoa heliodiscus we have here in Japan, seem to live off both zoox and zooplankton in the water (in nature). Most shallow-water zoanthids (Palythoa/Zoanthus) seem to be fine with just light, but from what I have seen on these threads, zooplankton and even bigger prey seems to be fine.
Do these hitchhikers of yours have large oral disks, narrow polyps, and are connected by a VERY small coenenchyme (tissue) to each other?
j.