Work on a new underground highway tunnel in Seattle has been ground to a halt over the last two weeks as a mysterious object has stood in the way of the massive tunnel-boring drill used on the project. While local historians and residents speculate that the object could be the remains of a lost shipwreck or remnants of Seattle's gold rush or prohibition-era past, engineers perplexed by the unexpected obstruction theorize that it is likely just a huge boulder that has somehow proven to be too unwieldy for the enormous drill. More on the story at the New York Times.