This artifact is known as a pipe tamper or letter seal.  It has the motif of a ship molded onto the face.  The story has it that this was likely a ring originally and was turned into a tamper because the ring did not fit onto the individuals hand anymore.  The most likely individual for this type of stamp to belong to was someone of wealth or influence on the ship.  

The HMS Eagle was a 3rd rate English warship and a sister ship to the HMS Association and two other ships set sail from Gibraltar on September 29, 1707.  Upon entering the treacherous English waters in a howling gale on October 22, 1707 the ships hit the rocks on Tea Ring Ledge off the Isles of Scilly.  All ships sank with over 1800 men.