A fluid-driven fracture propagates radially in a transparent hydrogel. The fracture surface 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. (No adjustments were made to the image.)
Petal-like fluid-driven fracture patterns —

A fluid-driven fracture propagates radially in a transparent hydrogel. The fracture surface 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. (No adjustments were made to the image.)

https://fluids.ac.uk/files/05_Photo.1512131214.png