strange yellow rootlike structure on sponge

[dilnepenthes]

Hi guys, found this strange yellow structure on my blue photosynthetic sponge and looking to see if theres anyone who could help me id it. It was not there this moring but when i came back home this afternoon there it was. I touched it with some tongs and as soon as i touched it, it broke apart and didn't show any reaction(shown in the third pic). Could this be apart of the sponge?

thanks

[Polarcollision]

I have the same purple photosynth sponge. Can confirm the growth is not part of sponge. 

 

Most of these HH are good for biodiversity —or— they fail to thrive. Wouldn’t worry about it.