Well now, I think it is a pontil mark caused by the use of the previous blow pipe used to make the bottle before it. They used to lay the previous blow pipe up by their glory hole to keep the glass on the blowpipe hot enough to stick on the next bottle. The other option was to keep punty rods hot and ready to be used for empontilling the next bottle blown. 'Another thing to realize is that the diameter of the punty rod had to be large enough to hold the size bottle being made. It it was an oval flask they need an oval punty rod working end. It it was a round bottle they would need a proper sized punty that would 1. Be the right diameter and 2. provide enough push-up in the bottle to hold it. and 3. Often show the identity of the lower. Witch told them who to credit for - or raise H with if something was wrong. I also think that some badly needed bottles had a bonus paid to get them fast enough. They also had to use different materials on the punty rod end to hold different bottles. Some blowers would use graphite powder, and these materials were left up to the blower's choice for the job. They had a multi-section box, with graphite, cast iron dust from the mold shop, sand, and some weird powders. I have several different looking pontils.RED M.