This demonstration shows how the pattern depends on the discreteness of the simulation, here modelled in terms of the number of mesh points. Run the simulations repeatedly (which will give different random initial conditions) and observe the difference between the two simulations which have the same parameters except for the mesh size of the simulation. (Note: The code used is a spectral one, which reduces mesh effects. A finite difference code such as might be used to model transport between discrete cells would show differences from the continuum version for even finer meshes.)