Sclerosponges are porifera with a soft body that covers a hard, often large skeleton made of Calcium Carbonate, either Aragonite or Calcite. A perfect example of this phylum would be the species Ceratoporella nicholsoni. Because of their long life span (500-1,000 years), it is thought that the analysis of the Aragonite Skeletons of these sponges could extend data regarding Ocean temperature, Salinity, and other variables farther into the past than previously possible. Their dense skeletons are organized chronologically, in concentric layers or bands. The layered skeletons look very similar to Reef Corals. because of this sclerosponges are also called coralline sponges. The living components are also entirely identical to those of the Demospongiae. Numerous spicules on their outer surface are somewhat raised. The cryptic habits of this class make them very difficult to study.