sedimentary

Bryozoan Fossil

Phylum Bryozoa (commonly known as 'moss animals')

Hardness: 3-4 (Mohs scale), Color: White to grey/tan, Luster: Dull to earthy (stony), Structure: Colonial skeletal lattice or mesh-work of tiny chambers called zooecia, Specific Gravity: 2.7 (calcitic).

Identified March 31, 2026More sedimentary →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Formed through the fossilization of colonial aquatic invertebrates that build calcified skeletons. These fossils can range from the Ordovician period (485 million years ago) to recent times. They form in marine environments where colonies grow on debris or the seafloor.

Uses & applications

Primarily used for scientific research (biostratigraphy), decorative aquarium specimens, and as educational fossils for collectors. In some regions, large limestone deposits composed of bryozoans are used for construction stone.

Geological facts

Bryozoans are often mistaken for coral, but they are more complex organisms. They can form branching, lacy, or massive stony colonies. Some fossilized lace-like varieties are known as 'Fenestellida'.

Field identification & locations

Identify by looking for a characteristic honeycomb or net-like lattice on the surface. Commonly found in limestone outcroppings and near ocean coastlines or dried lake beds. Collectors should look for intricate, unbroken lace patterns.

Other sedimentary specimens

See all

Sandstone or Siltstone

Arenite (if sandstone)

Sedimentary

Sandstone

Arenite (primarily SiO2)

sedimentary

Shale or Slaty Mudstone

Argillaceous sedimentary rock

sedimentary

Chert Breccia

Brecciated Chert (Microcrystalline Silica)

sedimentary

Sandstone (Quartz-rich)

Arenite (SiO2)

sedimentary

Sandstone (with man-made markings)

Arenite (composed primarily of Quartz, SiO2)

sedimentary