Strange growth under 1 coral rock good/bad?

Question
Hi Jennifer, I was checking out my tank today and found a strange white/clear growth on the underside of one of the corals.  I can't tell if this is good or bad because I'm not sure what it is.  In spots there is clear see thru cones.  The growth is about the size of a medium hand span.  I've also been using a new product called Fuel!  Any ideas?

thanks
Mike

Answer
Hello Michael. You are using the RF Fuel? I have heard of it from a couple of our customers but have never used it . I did hear some good things about it and no bad things yet. First of all I have to ask, Are you one of those people who peeks around their salt tanks with a flashlight to discover new and interesting creatures you didn't even know existed in your aquarium? I know I am! What you are most likely seeing is some sort of sponge. I am not sure of the specifics but I have seen them before and am pretty sure I can picture what you are talking about.There are many ,many types of sponges that can come in on live rock or even the rock that a coral may be attached to. Does it almost have a lacey appearance? Is it attached to the rock? Or the actual coral? Does it look slimy or soft but firm?(if that makes any sense).Do the cones go inwards towards the rock or outwards?( I am trying to get a good visual). I don't think the growth you are seeing has anything to do with fuel since that is food for your good bacteria. I don't think it is anything you have to worry about but without seeing it I cannot say I am 100% sure it is a sponge.