Calvert's arms are vertical bands of black and gold, with a counterchanged diagonal bar across them. Crossland's are a quartered field of red and white, with a large cross bottony overlaying where the quarters meet. These arms were used as a symbol of Maryland since 1600, and was adopted as Maryland's state flag in 1904. It is the only state that has truly heraldic arms. Dun Carraig's arms use design elements from the arms of Crossland.
Some heraldic researchers believe that the Sea Dog was based on early descriptions of a beaver.
Since Dun Carraig is surrounded by the Potomac and Patuxent Rivers, as well as the Chesapeake Bay, this maritime creature was chosen as our symbol. A Sea-dog rampant to sinister gules.