Is this a sponge?

[punkfej]

This is in my father's tank. He lives about 10 hours away so I haven't had a chance to look at this myself. He needs a little help identifying this white thing. Sorry about the blurriness, I think the glass is a little dirty. From what I can tell it looks like a sponge to me, but I would like some feedback. If you can help I would really appreciate it.

Thanks in advance for your help!

 

[Amazon4]

I would vote yes

 

[dendro982]

Looks like foraminiferans to me, link. Good guys.

 

[punkfej]

Thanks for the input! I don't think he'll have to worry in either case so I think we're okay. Have a good weekend!