We added 30lbs of base rock from Tampa Bay Seawater a week ago and just noticed a couple of these living in our rock. The “arms” (maybe around 8 of them?) are white/clear with brown bands, coming from a cream-colored center edged in red. When touched with tongs, it quickly retracted back into the rock. We would really appreciate an ID, and how to get rid of it if necessary. The tank is currently empty other than the live rock and Carib Sea sand, and it is not an issue for us to remove the rock to treat it, if that is better.