Any ideas, im not woried just curious

[Ericwm]

I saw this a few weeks ago after I got my lobo. It hasn't moved but I think it is living. It is attached to the skeleton of my lobo in the middle on the picture. It seems to close up against the skeleton at night and lift away slightly in the day, the little fuzzy white things seem to extend a bit in the day too. I haven't seen it do any harm so I'm not worried I just like to know all the creatures in my tank.

 

[Qube]

I saw this a few weeks ago after I got my lobo. It hasn't moved but I think it is living. It is attached to the skeleton of my lobo in the middle on the picture. It seems to close up against the skeleton at night and lift away slightly in the day, the little fuzzy white things seem to extend a bit in the day too. I haven't seen it do any harm so I'm not worried I just like to know all the creatures in my tank.

I had something similar on my wall hammer, turned out to be a sponge.

 

[Ericwm]

I don't think it's a sponge, it has what looks to be a hard shell on it. The "shell" is the same color as the skeleton because it has the same coralline algae on it.

 

[Ericwm]

Any other ideas. I know about the pineapple sponge on the side of the picture I'm curious about the thing in the center. It looks like it has little fuzzy white things around a shell, it opens away from my coral in the day and sits flat against it at night.