Is this a sponge?

[Gigi197]

I no longer have any corals but this blue/black looking "slime" has started to show up on my live rock. There's more underneath the rock but this is the best picture I could get. Is this a sponge? Should I worry?
Most recent parameters:
Salinity - 1.024
Nitrite - 0
Nitrate - 5.0 ppm
Ammonia - 0.0 ppm
PH - 8.0
Phosphate - 0.25 ppm
Calcium - 240 ppm
KH - 179 ppm

 

[blaxsun]

It's a possibility. If don't think it's necessarily anything to be concerned with. Is it "jelly-like" when you touch it?

 

[Garf]

Calcium 240? Typo?

 

[Gigi197]

It's a possibility. If don't think it's necessarily anything to be concerned with. Is it "jelly-like" when you touch it?

Yes, not quite "slimy" but jelly like

 

[Sleeping Giant]

Yes, not quite "slimy" but jelly like

looks like it is a sponge

 

[Cristy17]

If its black, I was told to get rid of it..haven't done the research to why its bad.