Is this a sponge?

[TheHumbleReefer]

Is this some sort of sponge growing on my rock? Its growing in the caverns of one of my rocks. Its slowly been spreading.

 

[Stephen Glover]

The white thing does look like a sponge to me.

 

[TheHumbleReefer]

Awesome! Other than silicates and plankton for food what do they need?

 

[Stephen Glover]

I don’t do anything special for mine. They grow nicely on the undersides of my rock.

 

[Nemo&Friends]

I do nothing for them, multiply, prefer shade.