Bryozoans are small, aquatic invertebrate colonial animals that often fossilize in intricate, lace-like or branching patterns. Collectors look for these specimens in marine sedimentary rocks, where they are commonly preserved as calcium carbonate structures or sometimes replaced by silica.

Hardness

3-5

Mohs

Luster

Dull to Earthy

Streak

White

Transparency

Opaque

fossilcommon

Bryozoan

Hardness: 3-5
Luster: Dull to Earthy
Streak: White
Transparency: Opaque

Is this bryozoan?

5-step field check

Run through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.

1
Test the hardness
Try to scratch bryozoan with a known reference. Bryozoan sits at Mohs 3-5 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Bryozoan leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Bryozoan typically shows a dull to earthy luster.
4
Match the color range
Compare against the expected color range: white, gray, tan, brown, cream.
5
Look at form & habit
Typical habit: colonial structures, branching, fan-shaped, or encrusting masses.

Often confused with

Bryozoan vs. its common look-alikes — and how to tell them apart in the field.

How to tell apart: Luster reads dull to earthy on Bryozoan and dull on Stromatoporioids.

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Often found alongside bryozoan

Minerals reported to co-occur with bryozoan. Spotting these in float or country rock is a strong cue you are in the right ground.

All properties

Mohs hardness: 3-5
Density: 2.6-2.9 g/cm³
Colors: White Gray Tan Brown Cream
Streak: White
Luster: Dull to Earthy
Transparency: Opaque
Crystal habit: Colonial Structures, Branching, Fan-shaped, Or Encrusting Masses
Cleavage: None
Rarity: Common
Uses: Collector, Decorative
Host rock: Sedimentary Rocks Like Limestone, Shale, And Siltstone
Typical price: $5-50 for small specimens, $100+ for large display slabs

Where rockhounds find bryozoan

Classic worldwide localities

United States
United Kingdom
Germany
China
Australia

Field-hunting tip

Look in sedimentary rocks like limestone, shale, and siltstone country — that is the host setting where bryozoan typically forms. If you start seeing calcite, dolomite, quartz in float, you are in the right ground. Field specimens usually show a colonial structures, branching, fan-shaped, or encrusting masses habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify bryozoan?+

Mohs hardness is 3-5. It typically shows a dull to earthy luster. The streak is white. Common colors include white, gray, tan, brown.

Where is bryozoan found?+

Notable localities include United States; United Kingdom; Germany; China; Australia.

How much is bryozoan worth?+

Typical asking prices fall in the range of $5-50 for small specimens, $100+ for large display slabs. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like bryozoan?+

Bryozoan is most often confused with Stromatoporioids. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with bryozoan?+

Bryozoan commonly co-occurs with calcite, dolomite, quartz, pyrite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does bryozoan form in?+

Bryozoan typically forms in sedimentary rocks like limestone, shale, and siltstone. Working float back to the host body is the standard way to chase a fresh occurrence.

What is bryozoan used for?+

Bryozoan is used in collector, decorative.

Find bryozoan on the map

RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.