A collection of gifs.

This is a 5-cell

Here is an animation of phonons

Gosper's glider gun from the Game of Life

A nice illustration of a Von Karman Vortex Street

A Knight's Tour is one that steps on all squares. A closed tour is one where the final square is one move away from the starting square. There are many (26,534,728,821,064 to be exact) on a regular 8x8 chess board.