Discover facts about the structure and life cycle of archaeocyathans, an extinct group of sponges, and view photos of fossils.

Review photos and descriptions of sponges that have skeletons made of calcium carbonate.

Sponge collection includes indigenous species, articles, and a comprehensive class breakdown.

View photos of sponges, and find links to other Web sites about sea sponges.

Examine illustrations and descriptions of Australian calcareous sponges, and find a classification guide. Also check the bibliography.

University of California, Berkeley guide to sponges covers ecology, habitats, fossil records, morphology, and links.

Devoted to the sponges of the Northeast Pacific region. See profiles of hundreds of Porifera, including photos and classification details.

Provides photos of sponges found in the northeast Pacific Ocean. Includes classes Calcarea and Hexactinellida (glass sponges).

Encyclopedia entry provides information on the aquatic invertebrate's anatomical structure, taxonomy, and commercial value.

Provides links to Web sites that offer details about the natural history of Porifera.

University of Michigan archive presents photographs, descriptions, and the traits of all four classes of sponges.

Profiles a group of sponges that contain spicules made of calcium carbonate.

Describes the structure of demosponges, and summarizes the taxonomic groupings of class Demospongia.

Presents a short profile on sponges, with photographs, diagrams, and a few links.