Shrimp/Crab with sweeping feathery arms/appendages

[TX_REEF]

Apologies I'm not able to get a photo because it retracts at the slightest hint of movement from me (I have to stay still for at least 30 seconds before it sticks out), but in my refugium, I have seen some sort of arms/appendages with hair/feathery material attached to them, sort of tan/sand colored, sweeping out from under a piece of live rock, sort of sweeping/pushing sand, sort of like digging but not as extreme. I want to say the appendages are .25" or so at most. Any idea what sort of crab/shrimp critter this might be attached to? It would have been a creature that came as a hitchhiker on TBS live rock. I do know that a small (.5-1") mantis shrimp was included initially, but I haven't seen him in over a month. More curiosity than anything, if you have any suggestions with photos that would be cool!

 

[Cthulukelele]

That sounds like a porcelain crab. They're almost always harmless filter feeders. Their long term tank survival isn't amazing though unless you're feeding some fine foods/phyto from time to time

 

[Cthulukelele]

Depending on the species they also host anemones! Also an aside but that was a pretty bang on description. Usually it's hard to tell what someone is asking about without a photo.

 

[TX_REEF]

you could be right on that, it's hard to tell for sure because I can only get a top down view, but the "mouth appendages" like in the stock photo below definitely could be from a porcelain crab!

 

[LiverockRocks]

Porcelain Crabs TBS Live Rock

Porcelain crabs are frequent hitchhikers on our rock. These guys are reef safe and easy to keep.

 

[Tired]

Barnacles can look a little like that, but the presence of arms does suggest it's a porcelain crab. Nice find- harmless and fun to watch. They aren't true crabs, and their large claws are used mainly for camouflage and scaring away predators, with a little bit of scooping at chunks of food. You can feed them powdered foods, but they'll also happily take pellets and frozen foods like you'd give your fish, and (as mentioned above) will likely need to be fed.