Each Mulberry component was given a code-name. The pier heads (Whales) and their roads ashore rose and fell with the tide on adjustable legs (Spuds). Submerged concrete caissons (Phoenixes), floating steel tanks (Bombardons), and sunken blockships (Corncobs) which formed an outer defence (Gooseberry), protected the piers. Components were built in different parts of the UK and were submerged off the south coast to conceal them until June 1944. They were towed to Normandy after D-Day.