New technology met ancient weaponry in Palo Alto this week when local park rangers used cell phone images and Wikipedia to identify an unexploded artillery shell discovered Wednesday in Foothills Park. The artillery shell is the latest in a long line of mysterious hazards that have periodically surfaced at Foothills Park since its official opening in 1965, offering another glimpse into its secretive history. Residents were alerted to the most recent episode Wednesday afternoon, when the city sent out a community notice warning that an unexploded World War I artillery shell had been discovered on the 3200 block of Alexis...