I did this in Bryce 3D - The Terrain Editors in Bryce 2 and 4 are almost identical to this, for all that matters.

Things To Do With Fractals In Bryce
Chapter 2: Fun With Lattices And The Multireplicate Dialogue

Have a look at my Dragon Star and download the object. You are about to learn how to make it.
I won't go into as much detail here as I did in the first chapter. If you are not clear about what "buttons to push" to import textures, terrain maps, etc, it's all explained in chapter one.

You need a Fractal against a black background. KPT5 FraxPlorer "M-Polar Variations" is a good place to start. I rendered the one below at 1024 pixels square, using the "Mosaic" colouring mode. If you don't have a program which lets you do Fractals against black, pick an area of an all-colour Fractal and black out what you don't need in your favourite image editing software.





Remember, to end up with a smooth terrain or lattice, the image map should be much larger in pixels than the grid size of the terrain or lattice you want to model on it. Unlike the terrain size, it does not need to be a power of 2.

Next, open a new Bryce document. Hide the Ground Plane in the Object Attributes dialogue and choose the plain black background from the sky presets popup menu. Create a Symmetrical Lattice, leave it selected and go to the Terrain Editor.
Set the grid size to 256, click on the "Pictures" tab, and import the fractal you just made. Pull the "Blend" control all the way to the left and click "Apply". Click the "Elevation" tab and click the "Smoothing" button just once.
You will notice the black parts of the original image overlaid with red. The red indicates clipping - clipping ensures that there is no mesh in the affected parts of a Terrain or Lattice. You can adjust the clipping level using the bracket to the right of the map. In this example I accepted the default.





On the popup menu under the triangle to the right, below the map, you should ensure that "smooth" is checked before clicking ok. If you increase your clipping or if you use Alpha Channell transparency with your texture, you may also want to check "solid".

Next, import the texture map, as described in chapter one of this tutorial. I chose the following matrerials settings for this example:





Feel free to experiment with the settings.

Hey, after adjusting scale and position and adding a few atmospherics, this looks pretty good already:





But we are not finished yet. We are going to multi-replicate this beauty.