Yellow sponge like thing in my gsp

[Franki]

So this yellow thing has appeared on my gsp. I think its a sponge. Ive seen smthg similar while diving and i use sea water in my tank so thats probably it. What do you guys think?

 

[James M]

It’s a sponge

 

[ndrwater]

+1 for sponge

 

[Gonebad395]

Sponge nothing to really worry about

 

[Franki]

Thx everyone. I suspected it was harmless, thank god.