hdtran said:
Mammoth,
You're absolutely correct that short of scuba diving and surveying the Tampa area, biology journals or field guides are the best source. But to those of us unable to locate either of the above, we have to go to secondary sources, e.g. Richard Londeree (liverock). I tend to believe him, as he's out there scuba diving in the gulf waters.
No doubt he is an experienced commercial diver, selling alot of great product.
Peterson Field Guides. Coral Reefs: Caribbean and Florida
Pale Anemone - Aptasia Tagetes
Small - about 2.5 cm (1 in) tall - brownish or whiteish, and a few long easily visible tentacles and many small visible on close examination. Disk usually 1cm (1/2 in.) wide, with almost 100 tentacles in narrow rings around edges. Usually in crowded colonies of unconnected individuals on rocks or mangrove roots.
Next to that description is a photo that appears to be indentical to what is on my small piece of TBS rock. It started with 1 tiny anemone, barely visible...6 months later I have at least 15 of them within a few inches of the same spot.
Another...
http://www.nsm.buffalo.edu/Bio/burr/world.htm
Since you seem to like Fenners work, there are a few hints in here. Nothing conclusive, but at least enough to suggest that it's not as easy as 'couldn't be'.
http://www.wetwebmedia.com/marine/inverts/cnidaria/anthozoa/twaanemones.htm
I'm not claiming to know exactly what it is, but it's fairly clear that it's possibly an Aiptasia Tagetes. I think the common name listed (Pale Anemone) creates some of the confusion...you'll find references using that common name for different anemones. Stick with Aiptasia Tagetes and dig around and it should at least enter the realm of possibility.
It's one thing if we have a positive identification of what these are. That's not the same thing as suggesting a few other possibilities and denying they could even be in the waters. Tell that to the student who recently spotted Right Whales, which haven't been seen in the gulf in roughly 30 years.