This strange blob that looks a bit like an island was generated by the same process as the Mandelbrot set described here, except instead of using z_0 = 0 in the z_n = (z_{n-1})^2 +c recursive function, it uses z_0 = (-1,1/2).
Also, following Alexandre Muñiz's suggestion in his nice post Children of Julia Sets, I used 255 iterations, and assigned the grayscale colour to the points based on which iteration they failed to converge. This gives the wispy archipelagos in the south of the island.
