This one is pretty nifty: Physicist Jean Rajchenbach and colleagues at the University of Nice Sophia Antipolis in France created star-shaped sizes by shaking a dish of silicone oil.
These unusual patterns are thought to spring out of non-linear interactions between three separate waves, but the mathematics behind the shapes is poorly understood. Weirdly, the star-shaped waves emerge in containers of different shapes and sizes, suggesting they are not affected by a container's edge - which usually explains a wave's shape. "It is extremely amazing," says Rajchenbach.
Read more over at the New Scientist: Link