A slow change such as continents moving will create differences in ecosystems. This is also the same effect caused by a rapid change such a meteorite striking earth. These two phenomena will create diversity and different living conditions. The slow change however, will give organisms time to adopt giving them a good chance of survival unlike a rapid change which will give most, if not all, organisms little chance to survive.
Answer:
Technically air. The air is the only thing known that we can, "hold" without ever having to use our hands for any known reasons. We're holding air right now. When you inhale or hold your breath, your lungs are holding air.
