An ironclad was a steam-propelled warship protected by steel or iron armor constructed from 1859 to the early 1890s. The ironclad was developed as a result of the vulnerability of wooden warships to explosive or incendiary shells. From Wikipedia
Season 3 casting for The Titan’s Curse features Levi Chrisopulos as Nico di Angelo, with Olive Abercrombie as his sister Bianca