Thanks Michael.
The tank is doing well, as is the QT process. All of the fish are eating well and active, but they seem more aggressive right now. I'm not sure if it is due to breeding behavior, or just stress from a QT environment. As far as the fallow display tank, I found a third anemone on the underneath side of the oyster shell that the second anemone adopted as home. I thought earlier that they were tube anemones, but now I think that all three of them are ghost anemones. The one that seemed in poor health that I moved from the 20g high to this tank seems very healthy again. Here is a video of it below, sorry for the poor quality. I'll try and get a better shot of it in the future. The anemone moved from a razor clam across about 3" of sand to the base of the largest oyster cultch, and has stayed there ever since.
https://www.youtube.com/watch?v=RuDLOu6vhKM
I also found another unidentified invertebrate. I think it is some type of worm, but I'm not sure. It has moved to another oyster shell since this video, so it's not completely sessile. Here's a video of it:
https://www.youtube.com/watch?v=uFZ7e_6rN5s
Most of the tunicates died off, but 3 of the larger original ones are hanging in there and seem to be healthy. I have two "new" ones that I've found that seem to be juveniles, about 1/4" wide now, one that I've found on an older oyster shell that I collected and also one on my cultch, which leads me to believe that they reproduced in my tank. The grass shrimp, mussels, barnacles, and the many bristleworms are also doing well.