Emerald crab is a mobile reef..

[ajespo85]

So at first I thought nothing of it, but my larger emerald has some nice coralline algae on this head, and... what at first I thought was a sponge growing from his "ear" area, is now a feather duster. It's been 4 weeks now, and he hasn't knocked it off, just walks around, doing his thing. We all laugh at him when it's out feeding haha. But anyways, is he ok? Do I need to step in and knock that thing off of him?

 

[Sugar Magnolia]

No, he'll molt and will grow a new exoskeleton.

 

[ajespo85]

ah, that's true. don't know why i didn't think about that.

 

[Shawn O]

got pics?

 

[Betta132]

I doubt it would bother him even if he wasn't going to molt. Feather dusters don't damage whatever they're on.
Honestly, I'd be tempted to stick a tiny bit of macroalgae on top of him, maybe wrap it around the duster. See how many species you can put on him before he molts!

 

[sam.basye]

I caught a hermit crab at the beach this summer with a large tube worm growing out and up from the center of the shell above its eyes. Looked like it had a horn. Lol