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