Thanks for the pic and description Don. I actually had those exact sponges
on the underneath of one of my live rocks as well. I had to pull that rock
out to clean off an aiptasia. Since I didn't know what those clear things
were on my rock I scrubbed it off. (I'm sure it will grow back as I wasn't
too thorough.) So basically, you solved another mystery for me. ha

Do they ever mature to get color or look like a sponge that we'd want to
keep/decorative? Doesn't look like it so far.

Thanks,

B



"Don Geddis" wrote in message
...
Bryan wrote on 8/11/2006 2:06 PM:
These things only grow on my star polyps. I can't figure out what they
are. Sometimes there's a few and sometimes there are several. I seem to
have a lot of them now. When the polyps are open these things are
totally
hidden. The star polyps seem very healthy. All water tests are perfect.
Each on has an opening at the top. I never see anything go in and out
so
it must be for nutrition...
http://www.geocities.com/bryg30/Unkn...tarPolyps.html

Wayne Sallee wrote on Fri, 11 Aug 2006:
Those are sponges.

I've got some white sponges growing on my star polyps also:
http://reef.geddis.org/a/Star%20Polyps/p/dsc05558.jpg
A little different species than yours (more of a mat with tubes, rather
than balls), but probably similar.

My white sponges only grow in the dark; they avoid anywhere the MH lights
touch. My guess is that it's a bit symbiotic (or maybe parasitic) with
the
star polyps. Namely, at night the star polyps retreat, so the sponges can
feed. But during the day the star polyps come out, making a light
"umbrella"
for the sponges to protect (?) them from the light.

My white sponge grows fine on the dark underside of my live rocks by
itself,
but the only times I see it out in the light is inside a mat of star
polyps.

-- Don
__________________________________________________ _____________________________
Don Geddis
http://reef.geddis.org/
If your friend is already dead, and being eaten by vultures, I think it's
okay
to feed some bits of your friend to one of the vultures, to teach him to
do
some tricks. But ONLY if you're serious about adopting the vulture.
-- Deep Thoughts, by Jack Handey