The type of rock created from hardened lava is called igneous rock. Igneous rocks form when molten rock material, known as magma, cools and solidifies either beneath the Earth’s surface or after being expelled during volcanic eruptions. When magma cools slowly underground, it forms intrusive igneous rocks like granite, which have larger crystals. Conversely, when lava cools rapidly on the surface, it produces extrusive igneous rocks, such as basalt, characterized by smaller crystals. This rock type is crucial for understanding the geological history of Earth, as it provides insights into volcanic processes and the planet's crust formation.