What is this??

[slick]

I found a few of these behind my overflow wall. They are small about the size of a pencil eraser or smaller. I have like 6 of them. I tried to take a pic but my macro is junk. I drew a pic in paint.

 

[slick]

drawing

 

[dpittman]

I have tons of those - my sump is full of em - they are attached everywhere inside my overflows as well -

 

[kpogue]

I have them as well in my sump and skimmer. I believe they are a harmless filter feeder. I have noted though they have about a 2 week life span then are replaced w/new ones. HTH

 

[saltywashington]

I believe they are called sea squirts. They are harmless and a sign that your tanks are doing great.

 

[rsd]

I've heard of them refered to as a vase sponge and I have lots. They have a high turnover rate but seem to reproduce well... my limpets love to eat em.

 

[scottbythesea]

See Hydroid post above,
Your fine they are not bad if they look bad on the glass srcape them free they seem to show up when a tank stables out .
I noticed mine a year after a tank begins to stable up and work within proper prameters...Then they show up on underside of the rock work and in the over flows first.
ScottbytheSea

 

[clarkiiboi]

Q-tip sponge(s). Harmless filter feeder. A recent thread just started yesterday to look at, but you can do a search using q tip sponge also for more info. HTH

 

[clarkiiboi]

forgot pic, but while getting the pic I remembered it has also been called a pineapple sponge.