We have a limit amount of this photosynthetic plating sponge available. These are loose cut chunks, which you'll want to wedge into a rock or tie down somewhere. 
 
This sponge grows similarly to montipora cap, but is SOFT! It'll move in the current and sometimes grow in a vase shape depending on flow.
 
Frags are 2-3" ea.
 
Avoid treating tank with chemiclean, as that will kill photosynthetic sponges.