Its a technique to get a macro shot without spending on macro lens. Just by reversing existing lens ( usually kit lens or prime lens ) and adjust everything manually ( including focusing, aperture ). required a lot of patients, practice and creativity. Best is to shoot in RAW format so it can be adjust easily.
Killer shot. The only nit, and it's really not all that important, is the edges of the photo. I think burning in a few areas might work.
But really, that's a very small thing. Otherwise I think it's an outstanding photograph.
Thanks for sharing.