OH OH OH!! thats a baby decorator crab! :D :D :D I KNOOOOOW FOR A FACT! :D
we have them like that at work all the time :) cute little good guys!
ETA: :grumble: i got too excited before reading the rest of the thread xDD
basically that little cutie is gonna grow and continue to change his wardrobe, whatever colors are in your tank thats whats gonna be on him... they typically stay away from corals (altho i have seen them with strawberry anems on top o their heads lol) its a possibility they might try a few....
We have those at the aq and they are actually pretty neat, He wont EVER pinch you (trust me, i've stuck tons of fingers into tons of claws and nada). We have one in our "holiday tank" and each holiday he gets different color string and pom poms.... he changes about once a month :) they have a velcro like fuzz on their exoskeleton that allows for the quick removal of stuff :) i guarententee once he gets bigger he's gonna blend in more and more.... we see bright red ones from time to time but they are a more tropical sub-species... which is obviously what you got! :D we have brown/reddishbrown ones here.... Crabs that get large enough to defend themselves don’t decorate their backs but for the plants and animals that settle down there and grow will live on, even when he molts :)
Decorator crabs recycle their living decorations during the molting process—they remove the anemones, sponges and other decorations from their old shell and use them to decorate their new shell.
:D