Dry lava is called igneous rock. The superheated molten rock that reaches the surface in an eruption is called lava, and lava may flow for miles before cooling.
When lava is underground in its molten state, it is called magma. Magma is less dense than the surrounding rocks and therefore moves upward. While moving upward, magma gains contact with the air and begins to solidify. It can either be solidified on the surface of the earth or in the depth of the earth. When the lava cools and dries on the surface of the earth, it is called volcanic or extrusive igneous rock. When it dries deep inside the earth, it is called plutonic or intrusive igneous rock.