These building stones are made of coquina, a type of sedimentary rock that is made up almost entirely of pieces of sea shells that are naturally cemented together with minerals.

Anastasia Island, which includes St. Augustine Beach where our beach house is, sits on a thick layer of coquina. This rock was quarried to build the large fort, Castillo de San Marco, as well as the smaller Fort Mantanzas, the St. Grancis Barracks, the Cathedral, and quite a few other buildings. These particular bricks are on St. George Street, beside my favorite bakery.

The Spanish used Coquina for the forts because it was the only building stone around, but it was an excellent choice. When the British attacked St. Augustine in 1702, the coquina absorbed the impact of the cannon balls instead of shattering as other stone would. The British attacked again in 1739 (The War of Jenkin's Ear), and again their cannon fire was thwarted by the coquina.