Need to know what this is!?

[Sheldon005]

I've got these growing on the backside and underneath my live rock.. Almost where there is no light...

I have no idea what they are or where they came from?

Any help is appreciated

 

[motortrendz]

it looks like a sponge..

 

[litoreef]

they are sponges they grow most of the time under the rock,,

 

[Sheldon005]

Awesome Ty!