I must be getting old. One of my brighter students asked me today to demonstrate a piece of physics with the irrefutable logic of mathematics. No, this wasn't a complex problem, but I found myself looking for an elegant, shatterproof piece of algebra that satisfied me, which I found a little bit demanding. Which led me, as spirals will, back to Fibonacci and I asked myself whether I could use a spreadsheet to reproduce a two-dimensional Fibonacci series as an equation.
This is how far I got in twenty minutes. I was quite pleased, since at the very least, it doesn't break any rules and at most, it's quite pretty. I might try again with a similar problem next year.