Bryozoa: "Moss animals" of the sea (PA-02)
Bryozoa, a group of aquatic animals that left their earliest fossil record near the start of the Ordovician Period about 500 million years ago, still live in large numbers. Although most bryozoans are hardly bigger than a comma on this page, thousands living together can form colonies many inches in diameter. The shape of a colony depends on the conditions of the sea bottom and of the water. Branching stemlike, lacy, massive or encrusting forms are common.

Many bryozoans are valuable guides to the age of rocks where they are found. And many lived in such great abundance that they held f principal roles in building limestone deposits, including reefs, that are now quarried. Bryozoa also help in interpreting ancient marine environments. So they are interesting and valuable for applied and scientific geologic studies.

Our Hoosier State Beneath Us: Paleontology