Looks like a transparent swirl - could be one of several companies. "Blizzard" named marbles have interiors that have a lot of "snow" or tiny flakes throughout. Here are a couple examples of Marble King "snowy".
Now back to the important part of this post since I am a bag collector (LOL). Here is a couple pics of a similar Champion bag that was posted by Alan B. some time ago. (Did not notice that it was same bag as Steph posted).