Final Cut Original Media

Final Cut Pro 10.4.3

I stored my libraries on an external disk, and I noted that the media corresponded to some of the libraries, It is contained on a folder named Final Cut Original Media.

If I rid off this folder, the corresponded libraries can not show the content once you open them, which is logic. But my question is what happened with the media corresponded to the other libraries. (I can open them and see the all media in each event)

I see the same store location settings for each library: Content, Motion, Caché, Backup etc. But I do not get to understand why the media corresponded to some libraries are stored on this Final Cut Original Media folder, and the other looks like it is contained in the each library itself. I need some guidance here.

Just to make mention I have read all the storage articles on the apple forum.