That could easily be an initial assumption of natural down too, so I wouldn't leap to that conclusion before investigating, though you may well be correct.

I should add that the leaves had been dried for weeks before I used them, and they are quite good at repelling water while alive. I found a little one growing in my yard the other day and it's one of the only things still living after a few frosts here.

It's an odd plant and one that I've been curious about since I was a kid. The leaves feel more like cloth than just about any I've run across.