(CNN) The hull of a ship, still sheathed in copper, and the numbers "2109" on a rudder suddenly appeared in the depths of the abyss.

It was an "unexpected and exciting discovery" that sea floor explorers from the National Oceanic and Atmospheric Administration made earlier this month while conducting a routine test of their new remotely operated vehicle, or ROV, in the Gulf of Mexico, NOAA announced

The number "2109" is visible along the trailing edge of the rudder. The pattern of nails securing the copper sheathing is also visible.

The wreck of what appears to be a mid-1800s, 124-foot-long (37.8 meters) wooden sailing vessel was first picked up May 16 by sonar on the ROV, named Deep Discoverer. Construction features such as the form of the stern and bow, the body of the hull, and the remains of the windlass gave hints that the vessel was built in the mid-19th century.

The discovery was made about 160 miles from shore, near the edge of the Florida Escarpment, in about 500 meters (1,640 feet) of water, officials said Thursday. The escarpment is a steep slope on the west coast of Florida where the sea floor plunges rapidly from relatively shallow waters.

While the vessel's rig, trade, nationality and crew remain a mystery, there is some evidence that the ship "caught fire and was nearly completely consumed before sinking," NOAA explorers said. Exactly when that might have happened, though, is still an open question.

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