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

 Igneous rocks & fossil

Fossils will not generally be found in igneous rocks.
Igneous rocks are formed by volcanoes as magma, granite and obsidian.

The heat of a volcanic eruption will destroy living things and only rarely preserves any evidence of them. Fossils are found in volcanic ash deposits, especially in Western North America.

Igneous rocks can also be pulled into the Earth and heated to form metamorphic rocks such as schist.