What might this be...

[dwmcnic_stu]

This white fuzzy thing has peaked my interest! What might it be? It is growing under/adjacent to one of my shrooms.

Thanks for looking and posting your thoughts. I appreciate it!
Edit: After zooming through some old threads via the search function, maybe a q-tip sponge, even though the top is different?

 

[valgae]

q-tip

 

[mr.clownfish]

+1 on Q tip sponge

 

[renogaw]

erm... qtips are usually only abot 1/4" long if that... this thing looks a lot bigger than any QTip i have in my tank

 

[spanko]

Not a q-tip, too large IMO.
I will go with a sponge of some sort though.
EDIT: OR MAYBE KING KONG Q-TIP