Barnacles are ancient arthropods that, as adults, are surrounded by a hard, mineralized, outer shell that the organism produces for protection. While extensive research has been conducted on the glue-like cement that barnacles use to adhere to a surfaces, less is known about the barnacle exoskeleton, especially the process by which the barnacle exoskeleton is formed. Here we present data exploring the changes that occur as the barnacle cyprid undergoes metamorphosis to become a sessile...