Plants played a crucial role in changing the Earth's atmosphere by using carbon dioxide from it. Long ago, when plants didn't exist yet, carbon moved from the air to rocky sediments. But when plants started growing, they stored carbon in their tissue, reducing carbon dioxide in the air. This shift increased oxygen and lowered carbon dioxide levels. Fossils of early plants show they adapted by changing the density of tiny holes called stomata on their leaves. As carbon dioxide decreased, plants developed larger leaves. This matches the drop in carbon dioxide levels caused by plant growth. So, as plants evolved on land, they transformed the atmosphere by using carbon dioxide to thrive and grow.