Common sponge? Or something else (pictures)

[Rick's Reviews]

Smothering my GSP but had noticed it on my rocks too

It's generally white in colour, looks abit like salt but has weird tubes.
Hopefully pictures will help

I moved my GSP to back of my aquriam a couple of weeks ago and noticed it was not flourishing as well, other corals are doing great

Thanks

 

[afrokobe]

looks like a common sponge to me. you could try brushing it off if it is bothering your gsp

 

[Rick's Reviews]

Thanks yes, it's been a common issue mainly on GSP, so thought I would check now I can provide better pictures