How to get an unmanaged version of a Realm object

Question

In accordance with this answer, all that is needed to obtain an unmanaged object from an existing managed object is to do this:

let unmanagedObject = Object(value: existingObject) 

However, when I do this, any fields of the existingObject that are themselves managed objects remain the managed object after copying. What do I need to do so that all sub-objects of the copy also become unmanageable?