Name this plant/algae/thing

At first it looked like a mass of roots gathered over my H. polysperma.
Then I found it was just sitting above them, i.e., was separate from the H.
polysperma. It feels and looks like netting, multi-branched, and very pale
blue-green in color. I certainly didn't buy it so it may have come in with
another plant. I have since removed it but wonder what it is. TIA.

Greg. Tong
gtong at sirius_com

"Often, the things that change are less interesting than those that stay
the same."--Aaron Fleisher