sorry guys, i know it was a vague question.. here are three pictures.. from far so u can get the idea of the size and then its zoomed in. its def not sand. it looks like some kinda deposit.. here pls help
<a href=showthread.php?s=&postid=15421454#post15421454 target=_blank>Originally posted</a> by otrlynn I'd just let it be. The rock may have been out of the water at some point long enough for the algae to die off. It may color up again, or new coraline algae will replace it.