A: It’s a crimping stake. In raising holloware, one method of angle raising used is to hammer radial crimps, or shallow folds, into the metal, making it look kind of like a paper cupcake liner. That holds the metal at a new higher angle. Then, using smooth raising stakes, the crimps are hammered in, upsetting the metal into itself, resulting in a smooth surface to the metal, now at the higher conical angle to the base, slightly thicker or stretched outwards. Anneal, repeat. Your stake is made for putting in those crimps.

Many metalsmiths do it over wooden crimping stakes rather than steel, as it results in fewer tool marks in the inside of the piece. But the steel stakes are handy, and can be used for other shaping tasks as needed.