Metaphor for an important discovery

"Joe Blogg's Damascus" can be used as a metaphor to denote a sudden turning point in attitude, behaviour or some other feature of Joe Blogg's life.

What would be a similar metaphor for an important discovery in a field such as artificial intelligence that does not necessarily represent a paradigm shift but does represent substantial progress? Ideas other than "Eureka" very welcome.

Also, would this be called metonymy? If not, what's the difference?

You could use expressions such as pivotal moment, turning point, kairotic moment. See here for some more choices.

The usual choices besides Eureka are epiphany (“An illuminating realization or discovery, often resulting in a personal feeling of elation, awe, or wonder”) and breakthrough (“Any major progress; such as a great innovation or discovery that overcomes a significant obstacle”) or breakthru.