Invertebrates, which represent more than 95% of the known species on Earth, are animals without backbones. Diverse, interesting, colorful, and unusual, marine invertebrates make great additions to your home saltwater aquarium. Not only are they great to watch, they also provide a great service to your aquarium as members of the "clean-up crew," helping to keep your tank clean of unwanted algae and uneaten food.
Many invertebrates are hardy, undemanding, and well-suited for the beginning hobbyist. Like anything you decide to keep in your tank, be sure to do your research as seastars can destroy corals and there are many different types of fish that love to prey on invertebrates.