Can Someone Identify This...

[Qix]

Excellent picture!

I like how you can see that they were laid in what looks like a continuous spiral around the branches. I'm starting to wonder if these things are only placed on submerged trees/wood. I don't recall seeing any of these on the bottom or on rocks or weeds. And although some were a bit deep, I believe all of them were at a depth where at least some sunlight would reach them.