Star-Shaped Waves

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