ID Please

[king_cobra]

These white things with a small tube protruding out of them are growing in my sump and see them in my display tank too. No idea what they are and if good or bad.

Thanks.

 

[Rtaylor]

Sponge or tunicates, harmless beneficial filter feeders

 

[ISpeakForTheSeas]

Sponges - harmless filter feeders.

 

[StatelineReefer]

I've been noticing a lot of this exact sponge making the rounds... it's longer lived than most hitchhiker sponges, and frankly interesting to watch grow as it paves the way for Coralline when removed, but hair algae will not grow where it's been, or grows a lot slower.

 

[king_cobra]

Thanks all! Glad to hear its harmless. Are there any specific conditions that are more conducive for these sponges to grow? Excess nutrients in the system?

 

[ISpeakForTheSeas]

Thanks all! Glad to hear its harmless. Are there any specific conditions that are more conducive for these sponges to grow? Excess nutrients in the system?

Yes (though what those conditions are exactly varies a bit depending on the sponge). Generally, the below should be a good guideline:

If there’s a high level of silicates and a sufficient amount of food for the sponges (including things like Dissolved Organic Matter, bacteria, phytoplankton, and some Particulate Organic Matter), then you may see a population boom with sponges.