Igneous rocks are called fire rocks and are formed either underground or above ground.

This is obsidian - an igneous rock.

Underground, they are formed when the melted rock, called magma, deep within the earth becomes trapped in small pockets. As these pockets of magma cool slowly underground, the magma becomes igneous rocks.

Igneous rocks are also formed when volcanoes erupt, causing the magma to rise above the earth's surface. When magma appears above the earth, it is called lava.

Igneous rocks are formed as the lava cools above ground.

Metamorphic rocks are rocks that have "morphed" into another kind of rock. These rocks were once igneous or sedimentary rocks.

This is sandstone - a sedimentary rock.

These little bits of earth are washed downstream where they settle to the bottom of the rivers, lakes, and oceans. Layer after layer of eroded earth is deposited on top of each.

These layers are pressed down more and more through time, until the bottom layers slowly turn into rock called sedimentary rock.

This is Geode - a sedimentary rock.