White/see through string on GSP

[Lil Puff]

Can anyone identify what this is on my gsp?

 

[ying yang]

If you mean first picture then kind of sponge I'd my opinion .if mean second picture,looks like tentacles off something but probably also same or another sponge, alot off sponges we get like the darker / shaded areas off our tanks and under corals is a great place.
I've found alot off sponges, just peel/ pluck off easy enough.
I've read most feel sponges are beneficial in our tanks,but also read a " reef builders " article saying why they think there bad,and goes on to basically say they use the same things corals need to grow,you can Google it to read if you interested .