What a great visualizer tool!

Observation: I never saw the link between Wave Equation Solvers, Finite Element Analysis (Eigenvalues, Eigenvectors, etc.) and Cymatics -- until I visited the above web page!

Related:

Cymatics: Chladni Plate - Sound, Vibration and Sand:

https://www.youtube.com/watch?v=tFAcYruShow

Cymatics:

https://en.wikipedia.org/wiki/Cymatics