Seashells are like a protective carapace for soft-bodied marine animals such as molluscs (eg oysters). There are about 100,000 types of mollusc shells and each has its shape and design, but they all develop in the same way. They are produced by the molluscs themselves, with a compound called calcium carbonate, which hardens and forms the layers of the shells. As the animal grows, the shell also increases in size so that its body can fit into it. To find out the age of the molluscs, scientists usually count the rings that form the shell, with each ring corresponding to a year. The Santa Isabel Biological Reserve is a Brazilian reserve designed to protect the coastal marine biome and stands out for hosting one of the research bases for the sea turtle conservation project, TAMAR, which has already released millions of hatchlings into the sea.