Any Idea What this is in My Star Polyps?

[Guy Cesario]

While rearranging some of my tank today, I notice this on the previously unseen side of my star polyps. Any ideas or does anyone know?
Thanks in advance...

 

[KJ]

Sponge.

 

[cracker]

looks like a type of sponge, At least mine have similar lattice structure

 

[Guy Cesario]

looks like a type of sponge, At least mine have similar lattice structure

Ok, sponges? Good? Bad?
Where do they come from?

 

[cracker]

TYhere are good filter feeders a sign of good tank perameters I'd think They are introduced on Live rock of plugs maybe.