Evidence for an iron plated turtle ship is found, according to Stephen Turnbull, in a 1795 drawing of the turtle ship where the shell is shown as being covered by a distinct hexagonal pattern, implying that there is something covering the wood shell. Hawley, however, questions the historical accuracy of this drawing since it departs in important ways from the 16th century ships such as its lack of the reported iron spikes (see image) and the different shape and number of the dragons' heads displayed at the bow. The Korean designation "turtle ship" is already attested in the year 1413, for an early type of the vessel which by all accounts did not feature any kind of armour.