can coralline be GREY??

[honda2sk]

i have a 1.5 yr old fowlr tank with live rock, fish. past month i see a large amount of a grey encrusting material on my live rock. looks similar to the pink coralline algae right next to it. is that what it is in grey? or is it something bad?

[Racing1]

Sounds like it may be an encrusting sponge. Hard to tell without a picture though...

[honda2sk]

has anyone ever seen grey coralline?

[TitusvileSurfer]

An encrusting sponge should have obvious inlets/outlets to process water.

This image is (supposedly) of an encrusting sponge I found online, although because of the angle its hard to tell. Anyway looks similar to what you are describing.

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