Live rock hitchicker I.D please help

Hi everyone I'm a noob to the saltwater scene so would love some help in I.ding the stuff I've found on my live rock.
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Circular white spots - micro featherdusters. Harmless filter-feeders.
Tubes - various tube worms and/or virmatid snails. Harmless filter-feeders.
Bivalves - unknown species, harmless filter-feeders.
Crab - electric blue hermit. Mostly harmless, but will need larger shells and occasional target-feeding.
White mass - sponge. Harmless filter-feeder that is usually short-lived (we tend to keep our tanks too clean for them).

 

Thanks for the reply in regards to the crab do I just get a bigger shell and put it in the tank. Also I've see a few a few really thin hair like barbed things stick out I guess there a worm but are they safe? Thanks again