Natural structures are formations created by nature without human intervention. These include mountains, rivers, caves, and forests, which are shaped by geological processes, weathering, and erosion over time. Each structure plays a vital role in the ecosystem, providing habitats for various species and influencing climate patterns. Examples of natural structures can be seen in landmarks like the Grand Canyon or the Great Barrier Reef. These formations not only showcase the beauty of nature but also serve important functions, such as water filtration and carbon storage, contributing to the overall health of the planet.