Gall Crab?

[hyperfocal]

I've got what I think is a gall crab in (what I think is) an A. miribilis. It's been suggested that the critter might be a barnacle, but it sure doesn't look like a bivalve to me. Can anyone take a stab?

Here's a shot of the opening in the acro, it's open space in there:

These next couple show the critter emerging to swing it's feathery claws around:

Retreated to cover, sick of the Paparazzi I guess

More shots of feeding:

 

[greenbean36191]

It's a barnacle. It doesn't look like a bivalve because it isn't. Barnacles are crustaceans just like crabs. Bivalves are mollusks like clams.

 

[hyperfocal]

Wow, did I end up getting confused. Somewhere along the way while trying to ID this online, I'm sure I saw a reference to coral barnacles that categorized them as bivalves. Either I mis-read, mis-remembered or the site was wrong. Anyways, thanks for the ID.