How to fix a object intersection problem?

The picture below shows some test graphics. In it, it generates some spheres that have a high chance of intersecting with each other; this is a needed effect. When I apply a simple transparent material to the exterior, I objects that are similar to what you see with purple image below.

What I ended up is not unexpected, I can see the interiors of the each sphere where they merge/intersect, but what I need is to be able to "exclude" the interiors, so that I see just the exterior (similar to the grey image ... I am still working with with semi-transparent textures; it's only for illustration).

Is there a way, at runtime, to merge two spheres together to produce a blob-like shape similar to the gray image below? Can I manipulate the spheres in some way, use a kind of shader, or something else? The scene is generated, so it has to work at runtime.