Admittedly I really don't know what it could be. First thoughts were some sort of texture of an animal, hair perhaps... but all these ideas just didn't seem right. Was this a longer exposure?
Yes it was, but I couldn't tell you how long. I was basically just experimenting, and I swung the camera from right to left while holding the shutter open for about a second (I think). It's a very pretty tree which was backlit by the sun. Pretty colors and I thought it might look cool. I'm a big fan of long exposures that cause blurring and I often try things like this without any idea of how it will look. I think it turned out pretty cool. I'm glad you like it.
Thanks for looking.