By combining negative and intersect booleans, you can create a matching set of irregular shaped objects for use as i.e., cracked eggs or as I illustrated here . . . a simple separating effect. Create and group a positive and negative object. Here, I used a rectangle as the positive and the terrain as the negative object.. Duplicate the set and change the negative object of the duplication to intersect. You should now have matching portions of the original positive shape. Select and Shift select both the positive and negative booleans. Use the Align tool to center the objects. They should be a perfect match. Now you can select and reposition both objects as desired.