Ever heard of coquina? This type of rock is made of various size pieces of shells and other invertebrates. It was quarried and used as building material all over St. Augustine hundreds of years ago. Most of the buildings in old town and the walls of the Castillo de San Marcos are made of coquina. It was essential in the fort and city walls as it would basically absorb cannonballs rather than shatter. These are a few of my shots from wandering around during my visit to St. A. back in July.