2019, diabase, 20 cm diameter
The spirals on the side and top are simple mathematical formulas. The spiral on the cylinder surface is a hyperbola of which I curled one axis around the cylinder. The spiral on the top, whose distance from the centre increases exponentially with the angle around this centre, took me a year of my PhD research. The photo above-right also shows the little sister, Eternity-1 from 2016.