There's no simple answer to "What's at the bottom of Earth?" because Earth is a sphere! It doesn't really have a "bottom" in the way we usually think about it.

But, if you're asking about the Earth's deepest layer, that would be the inner core. Here's a breakdown:

* Crust: The outermost layer, where we live. It's thin and rocky.

* Mantle: A thick layer of hot, semi-solid rock. It's the largest layer by volume.

* Outer core: A liquid layer of iron and nickel.

* Inner core: A solid ball of iron and nickel at the Earth's very center. It's extremely hot and under immense pressure.

So, the inner core is at the very center of Earth, but it's not really a "bottom" in the traditional sense. It's more like the heart of our planet.