Black Algae on Live Rock?

[Skylar Oborny]

I need help determining what this black substance is on my live rock. There has been more and more appearing in my tank. If more information is needed please let me know. I really dont know how to describe this.

 

[Aquarian]

They look like sponges to me. Here's some that are in my tank

 

[Skylar Oborny]

were they just live rock hitchhikers or where did they come from?

 

[ErinCahir]

+1 sponges. and yes. Hitchhikers.

 

[Aquarian]

Yes they were hitchhikers.

 

[Skylar Oborny]

Thanks guys! Much appreciated!