Does JME3 attach a unique ID to every element of a scene?

JME spatial’s “unique ID” is that it’s a Java object. It is its own unique ID. Nothing in the JME world ever needs to reference an object by anything other than its object reference. If your game setup needs to have some kind of redundant unique ID then it can use the user data attributes of the spatial to set that. But JME itself has no need for such a thing… and enforcing something arbitrary would be super bad for the games that don’t need it or use a different type of ID. You are also welcome to name your spatials uniquely if you want to more easily look them up using the scene graph API. …but again, what you name them and how you decide what’s unique is up to you and your game. JME intentionally tries to stay out of the way of making ‘game-specific’ decisions for you… that way something that works for 20% of games doesn’t make the other 80% harder.