Clear tube ID?

[bubbaque]

I have noticed I am starting to get these clear tube like growths all over in my sump and starting to get it in the main display. I have no idea what it is. The white rock is from the sump and gets no light and still grows fast. The other pics are from it growing on the side of my skimmer and then a little from the bottom of live rock in the display. Any one know what they are?

 

[KJ]

Sponge.

 

[bubbaque]

I googled for sponges that look like it and couldn't find any.