The control center of your nervous system.
A nerve cell.
A group of neurons that carries signals from the brain to the body and from the body to the brain.
The tube of nerves that runs through your spine.
Earth's outer layer; includes the rock of the ocean floor and large areas of land.
The thickest layer of Earth; found just below the crust.
The dense center of Earth; a ball made mostly of two metals, iron and nickel.
Continent-sized slab of Earth's crust and upper mantle.