[fishbait]

Wow - thank you for your responses. I am so impressed that some of you took the time to try to alter the picture for a better look. I am so grateful!

Here are a few more pics if anyone happens to check back on this thread. I took a picture of how it spreads to the sand (in little spots - this took about a week to develop), and another macro of the stuff on the rocks. It grows in the lower part of the tank, in lower current areas.

I like that comment about fast=bad, slow=ok - this was something that has developed over a month... My big worry was Cyano, but I've heard it comes very quickly. If it is some kind of coraline, it is not like any I have seen from pics online.

So if it is somewhere between - is there a point where too much of it can be detramental? How do I curb the growth (I know I could also try to get rid of it completely, but if it's not harmful, I would rather not).

Again.. I'd appreciate your feedback.