I wanted to teach my graphics class ray tracing and procedural texture. It seemed important to use a shape that is in the public domain, so that the students could use it as a starting point and would feel encouraged to create their own variations.
And what could be more "public domain" than H2O, the shape of a water molecule?
Below, I've placed the humble water molecule into situations of varying dramatic texture. Each situation provides a way to introduce another use of procedural texturing.