Horia's Marine Biology Page
Includes pictures of some hydroid species, urchin (Paracentrotus lividus) development, and other marine invertebrates.
Offers images of starfish, brittle stars, sea urchins, feather stars, and sea cucumbers.
The Echinoid Directory
Sea urchins: what they are and how they live, plus a fully illustrated guide to the identification of genera and higher taxa.