Thanks for the pointers, rezagamertag.
Maybe I might have gotten the wrong concept. I grouped them as the "obstacle" family that the player need to avoid.
I'm creating an instance of the obstacle, rather than the object. A random object will be created - so could be tree or animal.
System: Every 3.0 seconds System: Create object obstacles on layer 1 at positionX, positionY
So, I am thinking of using the onCreate to check the object, then reset the position and set the velocity for Y if it's an animal.