Hi Lizzy. That's a great picture. Definitely the closest thing I've seen yet to my "anomaly". (Nifty word!)
Your pigtail appears to be multi-colored. Do the colors match with the marble?
That may sound like a *duh* question, but bear with me. I have a definite idea in mind.
Picture a striped sheet on a bed. If it has a serious wrinkle in it, then you might have a wad of extra sheet material gathered above the main sheet. And that wad of sheet might be striped.
At first glance, the striping on the wad of sheet might seem out of sync with the striping of the main sheet underneath it, but you should still be able to tell that it was the same material with the same stripe pattern and it was actually drawn up from the sheet underneath it.
Glass being drawn up in a wrinkle or crimp or pigtail might smear in a way that cloth would not, but there's a good chance that enough of the striping would be preserved that you could see that it was probably pulled up from the main glass of the marble. As opposed to a separate piece of glass being imbedded in the marble.
Does that make sense, and does the coloration of your pigtail match the marble underneath it in that manner?