A mystery ship unearthed during construction of the new World Trade Center site isn't so much of a mystery anymore. A new study based on analysis of tree rings in its wood reveals that the ship likely got built in 1773 in Philadelphia—and with the same white oak used to build parts of Independence Hall, Live Science reports. After the skeleton of the ship was discovered in 2010, researchers excavated it and began the task of unraveling its origins. Scientists matched the ring patterns to those found in both living trees in Philadelphia and to wood samples dating back to the days when the city had a thriving shipbuilding industry. The rings patterns, shaped by climate, constitute a sort of tree "birth certificate," explains the Maritime Executive.
But the keel of the ship was really the key to narrowing the search—it was made of hickory, which grows only in the eastern US and eastern Asia, and researchers say the latter wasn't much of a possibility. So how did the 32-foot hull end up where it did? One theory is that it was a merchant ship that sailed for years along the Atlantic and in the Caribbean and eventually got buried by 1797 in a landfill being used to extend the shoreline of Manhattan, reports DNA Info. To see some pictures of the ship, click here. (Archaeologists also recently uncovered the Santa Maria.)