Crinoids (echinoderms related to sea stars and sea urchins) dominate the Paleozoic shallow water habitat in this illustration. They evolved a variety of stalk heights, which enabled them to capture food at different levels above the sea floor. The base of their stalks was modified to anchor the animal securely in the soft sediment.

Crinoids were relative skyscrapers in the community, sometimes towering up to two meters (6.5 feet). Lacy bryozoans occupied a lower level. Below them, huge numbers of brachiopods monopolized the muddy bottom. Sharks cruised above these crinoid forests, while smaller bony fishes weaved among the crinoid stalks. Explore the ancient ocean in an image gallery or in our Ocean Over Time interactive.