A fluid-driven fracture propagates radially in a transparent hydrogel. The fracture surface that is revealed post-experiment consists of beautiful fractal patterns called step-lines. These are small changes in height along the surface of the gel, which follow a logarithmic spiral shape. (Raw image)
Petal-like fluid-driven fracture patterns —

A fluid-driven fracture propagates radially in a transparent hydrogel. The fracture surface that is revealed post-experiment consists of beautiful fractal patterns called step-lines. These are small changes in height along the surface of the gel, which follow a logarithmic spiral shape. (Raw image)

https://fluids.ac.uk/files/04_Photo_180331.1522825624.png