Is this algae, coral or sponge?

[stormystormy11]

:blueflowe I thought this rock was really pretty so I bought it but then I thought I had better find out what is on it before putting it in my new 75 gal. It is soft to the touch like velvet and can flake off.

 

[Waddi]

Coraline algae?

 

[ANDREA]

i think is not good for your tank...
coraline is not soft, personal suggestion do not put that in your tank..

 

[stormystormy11]

I put it in my 20 gallon 4 days ago...can I take some of the other rock out and put it in my 30 g until my 75 is ready or has it already spread?

 

[Bifferwine]

That's black sponge. It's reef safe. Nothing to worry about, but if you don't like it, you can peel it off.

 

[stormystormy11]

It seems to be kinda going away on its own. I have it at the top of the tank under the lights. Thanks for the info..one more thing not to worry about.

 

[stormystormy11]

Okay, looked up black sponge...this is dark purple...still the same thing?

 

[Bifferwine]

I think it's the same. It will do better out of the light, in the shade.