What is this between my green star polyps?

[Jhoussock]

There is something between the polyps of my gsp. It’s only visible when they close for the night and doesn’t seem to be a problem. Curious what it is though...there is a torch near by that I’m sure is stinging it but it only has this stuff in this spot and the torch touches it everywhere

 

[Auquanut]

Looks like sponge.

 

[Leadfooted]

Looks like a sponge of some sorts to me.

 

[cracker]

it's a sponge I have the same sponge in my tank

 

[Jhoussock]

Should I remove it? Will it spread? It’s been there a few months and hasn’t hurt anything yet...