Please ID?

[liquorfish]

Puchased some new LR about 3 weeks ago. Over the last 2 days I just noticed this white stuff growing on the side of the LR and a few other spots on some of the other LR in the tank. Only LR in the tank, no inverts or fish.Could this be some type of sponge???

 

[flydan]

Hey,
It could be a sponge although if they are supposed to be white they usually grow on the underside of lr out of the light. I would leave it be and see if it gets some pigment over time. I had a spot like that that turned green after about 3 months and then started to spread.
HTH,
Dan'l