PIC: What conditions would cause this sponge to fall off and die?

I got the peach colored sponge in the top/right of the pic below, as a hitchiker on my LR. It lived for one month and constantly opened/closed/filtered water. Are there any params outside of what I currently test for (Ammonia, Nitrites, Nitrates, pH), that would kill this sponge, if not in balance?

Top/right:


The other (orange) sponge that hitchhiked on another piece of LR, is still living and breathing (top/middle of pic below):


Top/right:


What would cause the peach sponge to die, but my orange sponge to live?

 

Sponges don't breath? Hmmm I guess I got something cooler than sponges. My LFS owner said they were sponges when I picked out those pieces of LR. They, in fact, felt spongy.

Any idea what they could be? They constantly open and close. The peach colored one had a single mouth on the front surrounded by what looked like 4 fingertips. The larger, orange one has a mouth on the front and a mouth on the top. Looking closely, there are soft, teeth-like things in the mouth (orange one only, not the peach one). They are filter feeders of some sort...I'm guessing.

 

http://www.google.com.hk/images?hl=...tle&resnum=2&ved=0CDUQsAQwAQ&biw=1260&bih=767

its hard to tell on your pictures but if they look like sponges and they seem to respire
then they could be Tunicates
do any of the images on the link above seem similar

Steve

 

Just this one


Wow I've never heard of Tunicates. You are both right...looks like they are sea squirters that have never squirted...just the occasional bubble. I wonder what could have killed the peach colored, smalled, smoother, cleaner tunicate.

 

If the upper one died
and the lower one is still alive

is it possible that when you did a water change, the upper one ended up out of water?
as these type of creatures dont do well if expossed to air

Steve

 

Nope. The upper one is the one that is still alive and both were fully submersed during all WC's.

It is possible, however, that the smaller one did not fare well when I had to remove all LR from my tank to flsuh out a mantis shrimp with cold freshwater. However, after placing back in the tank, the sponge lived healthy for almost one month....so that can't be the culprit. Also, the larger one is still alive and was exposed to air just as long (quite a bit of time).

 

Mechanical filtration is the stock filtration on the BioCube29 HQI but my Chaeto in chamber 2 catches alot of waste too. I tried target feeding Rod's like I do with all of my corals but it just close up its inhalant Siphon and wanted nothing to do with the food

I bet you're right about the other one starving...