Uncovering Concreted Shipwreck Crossbow

3D Model

When iron and steel objects from a shipwreck fall to the sea floor, they corrode. In that process, calcium carbonate from the water, along with sand, shells and coral, attach to the surface of the object and mix with the rust. Over time, a dense layer of concretion fully encapsulates the artifact. Sometimes, the original metal corrodes away completely, in which case the concretion is left to serve as a mold. Here we have a crossbow found on the wreck of the 1564 galleon Santa Clara that has been cast of epoxy resin from its concretion. The resin has set in the void left by the decayed steel bow; the concretion has been partly removed in the laboratory, and the form of the crossbow is beginning to emerge.