Fuzzy White "tubes" on live rock

[roypersson]

Hello,

Recently I've been noticing some fuzzy white looking tubes growing on my live rock. They seems to grow on the "dark side" of the rock (always underneath / in corners).

Fish and inverts seem totally fine. Also found it in the sump tank. Seems to spread easily. I've picked off quite a few but cant get rid of it.

What the heck is it!!!

Regards,

 

[tunicata]

Hm, my first thought: sponge

http://www.wetwebmedia.com/PicstobePlaced/liverockspongeOct28.JPG
http://www.aquariumarts.com/yellowsponge.jpeg
http://www.advancedaquarist.com/2011/6/inverts2_album/IMG_2736.jpg

I get them/have them and they grow in the low light, lower flow areas. They've never harmed anything in my tank.

 

[roypersson]

first link shows it perfectly. Cool deal thanks!