What is this?

[atlfishes]

What is the white column thing? It is also appears to be hollow. These are popping up all over my tank.

 

[Paintbug]

Scypha sponge aka Pineapple sponges, harmless filter feeders

 

[Konadog]

Signs of a maturing tank!

 

[atlfishes]

Thanks, I've only had the tank running since Oct.