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I think it is "extrusive Igneous rock". Well, the magma,the hot liquid earth material which flows out through a vent(ways or cracks in the earth's crust), if on coming over to the surface of the earth, cools or solidifies, it is called "extrusive rock". If the magma, cools before coming over to the surface of the earth it is called "intrusive rock". the rocks formed this way are generally Igneous rocks. More detailed answer may follow.