Does anyone know what this is growing in my tank?

[brandowelsh]

I have an aio Fluval evo 13.5 and I have a strange growth in the first chamber of the sump. Can anyone identify what it is? Thanks in advance!

 

[neonreef3d]

looks like sponge

 

[Zach B]

Looks like a sponge of some sort

 

[Reefkeepers Archive]

Sponge

 

[brandowelsh]

Sponge

Harmful or no?

 

[Reefkeepers Archive]

Harmful or no?

Harmless filter feeders

 

[KK's Reef]

Harmless sponge, but I found them to thrive in-between zoa polyps. Bought a pygmy angel and now they are completely gone in the display.