Wherever you have fluid, there you can also find vortex rings.

Now, scientists have found vortex rings somewhere fascinating — inside a tiny pillar made of a magnetic material, the gadolinium-cobalt intermetallic compound GdCo₂.

If you’ve seen smoke rings, or bubble rings under water, you’ve seen vortex rings: doughnut-shaped vortices that form when fluid flows back on itself after being forced through a hole.