Continuing my self-imposed no-photos-for-one-week rule, I decided to rediscover POV-Ray (freeware raytracer) a bit. The current version has some features I never tried before, like isosurfaces (this rock is one).

It's still great fun simply placing objects, playing around with shapes/parameters and seeing what happens, especially now that I have a PC that can generate images like this in a couple of seconds. When I first tried POV-Ray ten years ago, scenes like this took two hours to render.

Related: You know you've been raytracing too long when...