Devils Tower is a natural rock formation. It's a laccolith, which is a type of igneous intrusion where magma pushes its way upward but doesn't actually reach the surface.

Here's a little more about its formation:

* Millions of years ago: Molten rock (magma) pushed its way up through layers of sedimentary rock.

* The magma cooled and solidified: This created a large, dome-shaped mass of igneous rock.

* Erosion: Over time, wind and rain eroded the surrounding softer sedimentary rock, revealing the hard, resistant igneous rock that forms Devils Tower today.

It's a truly impressive natural wonder!