Circles on glass ?

[Spn]

Just want to know this European sparkler has these perfectly round cycles either side  I’m just curious to know what they are from 

[Fire1981]

That's just weird defect from the rollers. It was probably a little glob of glass that got smushed when it was rolling on the rollers. That's just a guess. It is interesting that it'd perfectly round.  

[Royal3]

Or it hit a loose screw head on the roller, or something else that was machined. Just an oddity in manufacturing but I tend to like such misfits. 

[Chad G.]

I bought an old crystal 5 gallon glass water jar of marbles at an estate sale once and like 1/3rd of them had these circles on them. Some even had chipping around the circular marks making me think it happened after manufacturing. Not just from one manufacturer either. I wonder if they were hit marks from some type of early marble gun ?? Still a conundrum for me ??  I threw them all out, the marks rendered them useless for collecting, now I wish I would have held onto a few at least.