This is a neat animation that I wrote in Java.

It takes a  moment or two to load. 

Be sure to play with the "Speed" and "Points" sliders.  The optical effects can be captivating!

Click here for: SandDollar                  ( Source Code is here)

Two other neat examples that I didn't write:

Check out this animated  leaves on a pond's surface. 

Techo Nerd Red Light Special! à Click here for a  facinating graphical display of a sort algorithm race.