How to integrate a Unity game into an Android app?

Currently when I export my Unity application for Android all I get is an apk. What I would like to do is take a native android application and include a Unity mini game inside of the native app that I can launch from my native app. I would also like to be able to pass data back and forth from the native app and the unity game. Is this possible? If it is could you point me to a tutorial or just documentation about this?