This little bugger is fast. All but the first of these new images was shot with flash at 1/500 -- as soon as the flash fired, it'd retreat.
Here's a shot of the opening, 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:
Barnacles are bivalves, which this critter obviously isn't. I should probably ask in the Inverts forum...