The aperiodic monotile / "einstein" / "hat" from David Smith, Joseph Samuel Myers, Craig S. Kaplan, Chaim Goodman-Strauss (see: https://arxiv.org/abs/2303.10798), but in a variety of formats. With the included OpenSCAD file you can build it with or without a lip. (By the photos, you can see I obviously prefer it "with".)

The kites can be combined to double-kites, which can be assembled into hats. While proving the aperiodicity of the hat, the turtle and a variety of similarly aperiodic shapes were discovered.

My congrats to Smith, et al. I'm not a tiling enthusiast, nor a mathematician, but I think it's a thing of beauty.