Various types of debris are scattered across the reef, including a number of barrel-shaped concrete objects. Local legend was that the concrete objects had been barrels of concrete on a ship or barge that had wrecked on the reef during the Civil War, but an analysis performed in 2008 showed that the concrete was a type of Portland cement produced between 1890 and 1923. Archaeologists have found evidence of an iron- or steel-hulled vessel with two masts that wrecked on the reef, but have not identified the ship. It is not clear how much of the debris on the reef is from that wreck.[1]