jdwreefer, you have a long tentacle (Macrodactyla doreensis) anemone there. The one you have is quite bleached and with time and proper lighting and water conditions will become a deep purple color. It should be kept in a deep sand bed (4-5 inches) of fine aragonite sand. If you don't have a deep sand bed in your tank, you can get a tupperware container, let the anemone attach to the bottom, fill the container with sand and place some liverock strategically in front of the tupperware so the container is concealed from sight. If that species isn't in a deep sand bed, it will continually move and eventually fail.
Looks like your perculas took to the anemone, though LTA are not a natural host for A. percula. Assuming you have bright lights and high quality water, the anemone should completely recover. It's best to target feed a couple of times per week until it's darkened up. Pea size pieces of fresh shrimp (like you would find in the seafood dept. at the grocery store), squid, krill, scallops (also fresh from the seafood dept.) would be good food choices.
Keep us posted.