List of non-MonoBehavior objects exposed to editor

Hello,

If I make a C# class

 public class Foo { public int p; }

And a script with a list of this class exposed

 public class script : MonoBehavior { public foo[] foos; }

It does not show up in the Unity editor to be populated with data,

I can have foo inherit from MonoBehavior, but now the class has to be placed into an entire object before it is accepted.

How can I go about this?