I discovered this moss, which I call floating moss as it floats. The moss grows down into the water and back up with air bubbles trapped in the stems.
1st picture taken 12/17/2012, but this island has been growing in my Claytower tank for weeks. I think since I set it up but I didn't notice it as first.
a little piece of U graminifolia growing on the right side.
Today, the moss does seem to be starting to sink but that may be the U graminifolia pulling it down. The U gramnifolia can be seen growing down into the water. I did add a tiny piece of compost to the island to try and feed it.