This is becoming a trend - another built-in feature of Rails that will seriously help Galaxia development.
You can use acts_as_tree in a model to make it, well, act as a tree.
What this means is you add an extra field to the database called parent_id that tracks object’s parents. Rails automatically manages this for you and adds extra methods for dealing with trees (things for accessing parent, ancestors, children etc.). Just like the post on type, this is something I was already doing with Galaxia but managing myself.