It looks like a sponge spawning.

Here is another example in a larger version:

http://www.oceanicresearch.org/jpegs...ing_sponge.jpg

You may have had a large ammonia spike from the break down of all of the
sperm and or eggs which were released in the water.

"DD" wrote in message
om...
I captured a photo of the most strange and fascinating myserty creature
emitting a constant plume into the tank. The trail of smoke appears
transparent, and flowing in vortices similar to what you would see in a
wind
tunnel. It continued ejecting this material for hours, seeming to have an
endless supply. Then in the days following, many of my corals died.

The mystery can be seen just below and right of center:

http://www.autonvs.com/images/MysteryReefPlume.jpg

Thanks ~ Dan