What is this?

Any idea what this is a picture of?

Ok, so it is a cellular automation, but where did the symmetry come from? Here is the generating snipit of python code.

   def getArray(self):
      if self.count == 0:
          out = random((self.w + 1, self.h + 1))
      else:
          out = self.data[:,:]
          out[:,0]  = 0
          out[:,-1] = 0
          out[0,:]  = 0
          out[-1,:] = 0
          out[1:-1,1:-1] = (out[2:, 1:-1] +
                            out[1:-1,2:])/2.
          out += .01
          i_s, j_s = where(greater(out, 1))
          for i, j in zip(i_s, j_s):
              out[i, j] = 0
      r = out.ravel()
      self.count += 1
      self.data = out
      return out