Looks like it could well be an early experimental bit of IoWSG to me. Good find for 99p.
I've got a flame pontil mark on a bit I could have sworn was the coachbolt mark - suzygpr found the slightly squidged flame when she was on holiday here, polishing my glass. :sun:
I saw a lion's face in a poster in a physiology lab. It was an enlarged stained section of a spinal cord.
The brain "sees" faces in random shapes, all it takes is something of a vaguely similar construction.
I don't pay the slightest bit of attention to folk seeing faces in toast or clouds or cornflakes.
Have a peek at the "Sold" archives at IoWSG, here - you'll see a couple of inside-out style vases with similar patterns to this bit you've found.
http://www.isleofwightstudioglass.co.uk/Sold_Archive-b.htm