Echinodermata - Characteristics and phylogeny of the spiny-skinned animals: sea urchins, starfish, and their allies.
Echinoderms - Descriptions of the major species of Echinodermata (starfish, brittle star, sea urchin, feather star, sea cucumber) with illustrations and links to photos.
The Echinoid Directory - Project based at the Natural History Museum, London, aiming to provide information for amateurs and the scientific community on this major group of marine invertebrates with a long fossil record.