Fossilized tubes that once served as the home of Hamulus squamosus, a marine worm in the Serpulidae family. Worms in this family still exist today in the world's oceans, and they build protective tubes to live in from calcium carbonate, sand, and mucus. Their soft bodies are rarely preserved as fossils, but their tubes can be found in great abundance. These fossils date to the late Cretaceous period, 150-200 million years ago.
Courtesy of the Geological Survey of Alabama