Aquatic creatures live in the water, for example.
Since human beings live on the land, we might be regarded as Terrestrial. Yet, despite our intimate connection to earth, every person I have ever met has one key element to which they strongly respond, and this element is not always Earth. This key is what I call a power element. To illustrate by way of generalizations, people who love to stand in the face of a rushing wind, or who cannot sleep during wind storms, are empowered by Air. People who perk up in hot, dry weather and who seem ever the figurative pyromaniacs are energized by the Fire element.