Which metal made the Merrimac and monitor?

The USS Merrimack (renamed CSS Virginia) and the USS Monitor were both constructed using iron. The Merrimack was originally a wooden ship that was rebuilt with iron plating to enhance its durability, while the Monitor was designed as an ironclad warship from the start, featuring a revolving turret and a hull covered in iron armor. This use of iron revolutionized naval warfare during the American Civil War.