Please ID!

Hi Everyone!
I need some help identifying what is on my live rock. I have had my life rock for a good 6 months now. I have spent hours looking on google trying to identify it and unable to find out exactly what it is. The best way to describe it is probably spider eggs. It's white, looks like cotton and has a opening on the top. Here is a picture, please take a look at it:
http://i1123.photobucket.com/albums/l555/mhmitsheather15/FullSizeRender 3.jpg
If you could please tell me what it is, I would highly appreciate it!

 

Harmless sponges is my best guess, I suppose they could be tunicates as well, but both are harmless and not invasive.

 

kind of hard to make out but look up pineapple sponge images

 

I agree with sponges

 

Thanks everyone for the fast replies! I'm new to this hobby. Could someone please explain to me exactly what sponges are? Are they a good sign, bad sign? Something I should take care?

 

you may find this helpful. Is a good quick reference and also has extended readme info on different things you may find in your live rock

http://www.lionfishlair.com/hitchhiker/hitchhiker.shtml

 

Looks like pineapple sponge from here.