small yellow balls the size of a dime with hairs on them

I got a 150lbs of live rock for free on Craig's list. The guys tank sprung a leak. They are covered with tons of blue mushrooms which is great but there are small yellow balls about the size of a dime with hairs comming out of them that I have never seen before and just wondered if they are good or bad? Don't have a picture now but can post one later :-(

 

Sounds like sponges. Need a pic for sure.

 

^yup.

 

That was going to be my guess too.

 

150 lbs of live rock free, covered in mushrooms? You, my friend, are my Craigslist hero.

 

I will have to take a picture because I left out that they look like balls. I guess it could be a sponge but I haven't seen any that looked like this the lights are out now so tomorrow. I just don't want to contaminate my tank with anything bad. Yes great score when I say there covered with beautiful blue mushrooms its an understatement for sure a conservative guess would be around 200/300 there everywhere on every rock. Its funnyy LFS had a frag of 3/4 small heads of the same looking mushrooms for like $40/$50 I don't really remember for sure because I was laughing so hard!!!! If thats the value I AM RICH!!!!!!!!!

 

Here are pictures

 

it looks like a type of sponge to me

 

It's a harmless sponge, good for the tank. Personally I'd be more concerned with that many invasive mushrooms. I can't eradicate them and they don't get along with my sps