If you recognize the effect it may be because you have seen it before:

http://www.complexification.net/gallery/machines/sandstroke/

http://www.complexification.net/gallery/machines/sandDollar/

http://www.complexification.net/gallery/machines/limbsandstroke/

http://www.complexification.net/gallery/machines/sandTraveler/

In order for this code to run you must first download and install:

• fast sand paint: https://github.com/inconvergent/fast-sand-paint
• fn: https://github.com/inconvergent/fn

The code also depends on:

• numpy
• scipy