Strange item needs ID

[svine]

Hi all,
I have noticed a strange item that I haven't noticed before and wondered if anyone could help identify it for me? The pic is not the best because it is so far in the back of the tank. It looks like a small pod with arms that extend out to anchor it to the rock. Any ideas?

Thanks

 

[svine]

Item in question is dead center of photo

 

[Tahoe61]

Above the coral skeleton I see a feather duster and what looks like a white sponge. If you could circle the item that would help narrow it down.

 

[svine]

It is directly above the feather. It is a spherical object with a small hole in it. It has several legs protruding anchoring it to the rock. Could this be a sponge?

 

[rudy]

It's super hard to see, but it may be a ball sponge, Tethya sp.
Pretty common and harmless.