If small objects can be anything, basically anything goes! People could go, ants could go, they are really tiny, use your imagination, and you could think of many possibilities!
The smallest objects are also the most numerous in the whole universe. Those are the Hydrogen atoms.
The most numerous objects that are big enough for us to see are the stars, but I'm not going to say that those are the answer. Stick with me here, and follow my reasoning.
The Kepler space telescope is discovering so many planets orbiting other stars outside our solar system, that it's beginning to look like MOST stars have planets.
Stars are bigger. Planets are smaller. If most stars have planets, then the most numerous objects that compose much of the universe are the planets ! (plus maybe their moons too)
Does this make any sense to you ?
Now I have to ask YOU a question: Are there any choices for answers to this question that you're not telling us about ?
The heat from radioactive processes within the planet's interior causes the plates to move, sometimes toward and sometimes away from each other. This movement is called plate motion, or a tectonic shift.
