White root looking stuff

ive noticed this stuff growing on my rocks... it looks like a root system of some kind. these are the best pics i could get of it. also there is on the bottom of the rocks like a sac looking thing almost like a sponge, but it has a hole in it like it was an egg sac. i dont know about that either. i think that they are related. they are soft so to the touch (lol kinda spongy)

 

It is a type of sponge

 

+1 It is a sponge.

 

I have the same/similar stuff in mine and I was told that they were sponge as well. I know they are great filter feeders but I dont like them. ..

 

Yea me either lol. They can actually hurt corals too. One type of sponge grew over half of a green star polyp rock I had. I ended up chopping the rock in half and throwing half of them away. Here's what they used to look like when I first set up my tank:

Here is what the sponge did to them:


A sponge also hurt some zoa's (luckily they weren't really one of my favorites). I confirmed that this was a sponge by bringing a piece of it into the lab and looking at it under a microscope.

It was in fact a sponge

Here is a pic from when I first started noticing the sponge:

And few weeks later...



Its great to have them in your sump/fuge, as they are great filter feeders. However, they are very unattractive in a display tank and some species can pose a threat to corals. As far as I know, they won't sting corals.. But they literally smothered out my GSP's and prevented the polyps from extending. It was not a pretty sight!

If you want to get rid of it, you can try a few things. First, you can simply just remove the rock and get rid of it. If this is not possible (b/c it is a vital base rock, or removing it will disturb a deep sandbed, etc), then manually try to remove the sponge from the rocks. You can try to pick it off, but what I found worked best was to just scrub it off the rocks using a toothbrush. Another option is to take advantage of the fact that sponges hate flow. You can point a powerhead right at it!

Good luck!