what could this be?

[sassi128]

Have this stuff all over my tank. Anybody have a answer, and a solution?:hmm3:

 

[SeaTila]

Yikes! I want to know also. I'm new so haven't seen that yet.

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[sassi128]

Some say sponge, some say algae, some say OK some say not OK. Just need good advice!

 

[firefly73]

sponge. and sponges soak up crap and clean the water. down side is if it dies or you **** it off it may release a heap of toxins. i have about 6 different (probaly heaps more )types in my tank i watch them if they look suss health wise ill remove the whole rock and run gac. if i move things around i give them a wide berth. yours being that white colour looks sickly to me but it may also just be the variety

 

[pyithar]

they look like sponges to me