When using PhysicsComposer and PhysicsDestructor, there is no way to group the returned geometry into islands. For many use-cases this is essentially.
This is especially true when using the PhysicsDestructor.
When performing fragmentation it is critical to understand how the resultant unbroken geometry is connected so that specific physicsbody can be used to connect them together. With this information you can then have separated (island) geometry move independent of each other.