Sponge or bacteria bloom?

[Thakki]

Tank is 4 month into cycle...bare bottom...not turned on the lights...75% of the rock is real reef dry rock and 25% is live. Dosed microbacter 7 and ammonia to kick off the cycle. Tank is fully cycled...after 3rd month mark I started seeing white sponge like thing at the bottom crevices...slowly started spreading on the bottom of the tank...anyone seen this before. Seem like a filter feeder to me.

 

[Flippers4pups]

Looks like sponge to me. Good thing to have.

 

[Thakki]

I think so too...but never seen it spread so much and fast...is it because the lights are not on yet?

 

[Flippers4pups]

I think so too...but never seen it spread so much and fast...is it because the lights are not on yet?

Most sponge like very little light and silicates.