Sponges and scarlet hermit (pics)

[Fishguy2727]

I assume this is some type of orange encrusting sponge. It is doing pretty well. I also have the normal beige live rock hitchhiker sponge (and apparently pineapple sponges as well). The scarlet hermits, should still be three total, are helping keep the green hair/turf algae to a minimum. (Note the filter feeders in the rock by the sponges.)
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[kaybee]

Do those filter feeders move (sort of like rotating left to right, like a parabolic radar dish?), and grab things out of the water? If so they might be some sort of barnacle or something, I've got three living with.'in' my favia and they sort of look like that.

[Fishguy2727]

Yes they do. I assume they are a type of barnacle. I know I have barnacle skeletons on some of my rocks, I think the ones some of those are on. I know exactly the movement you are talking about.