Black spots

[Paulm7373]

Can anyone tell me what these black spots are on this piece of live rock? They are roughly the size of a finger nail but smaller.

[melosu58]

Are they hard or soft?

[Paulm7373]

I haven't actually touched it with anything yet, but it looks like it could be a soft surface and is slightly raised in the centre.

[melosu58]

I remember back years ago I had some black spots that was like a sludge and kept growing. I finally siphoned it up when I did a pwc and have not seen it since. You'll need to decide if it is trash or something living.

[Paulm7373]

It actually does look like small patches of black sludge.