I own one of these very things seen below, a Lichtenberg figure, created by irradiating a block of clear acrylic with a beam of electrons from a 5 million volt particle accelerator. Mine is a small flat cube of acrylic, and the pattern is nowhere as complex as this one, but it’s still cool to own what is essentially a fossil of lightning.
Photo from http://capturedlightning.com/
You can see how these are made here, spend some time digging around the web site, there’s videos of these being made, once the initial discharge, bolts of lightning keep flashing and etching paths inside the block for minutes afterward. It’s very cool. Captured Lightning.
The image above is an example of the path of lightning captured in a block, and now researchers are using it to create a template upon which an artificial organ can grow.Researchers create a template upon which an artificial organ could grow. They can grow blood vessels close to the natural patterns of blood vessels, which are fractal patterns to begin with. Link