I moved my pair of pom-pom ("boxer") crabs into my 12g nano, so now I get to see them more. Last week, one of them was perched in the middle of my open sun coral. Wish I'd gotten a picture.
Amazing crabs I love them, mine just molted. Very interesting to watch as they wave their pom poms around. They do well in a refugium, and their easier to catch a glimse that way if you happen to have a big tank.