Echinoids are the fossilized remains of sea urchins, often found as spherical or heart-shaped mineralized tests in marine sedimentary deposits. Collectors look for well-preserved ambulacral pores and distinct five-fold symmetry patterns on the surface of the shell. They are frequently discovered in chalk beds or limestone layers that were once ancient sea floors.

Hardness

3-4

Mohs

Luster

Dull

Streak

White

Transparency

Opaque

fossilcommon

Echinoid

Also: sea urchin fossil

Hardness: 3-4
Luster: Dull
Streak: White
Transparency: Opaque

Is this echinoid?

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 echinoid with a known reference. Echinoid sits at Mohs 3-4, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Echinoid leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Echinoid typically shows a dull luster.
4
Match the color range
Compare against the expected color range: white, gray, tan, brown, black.
5
Look at form & habit
Typical habit: test (the hard shell or skeleton of the echinoid).

Often found alongside echinoid

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

All properties

Chemical formula: CaCO₃
Mohs hardness: 3-4
Density: 2.6-2.9 g/cm³
Colors: White Gray Tan Brown Black
Streak: White
Luster: Dull
Transparency: Opaque
Crystal habit: Test (the Hard Shell or Skeleton of The Echinoid)
Cleavage: None
Rarity: Common
Uses: Collector, Decorative, Educational
Host rock: Sedimentary Rocks Like Limestone and Chalk
Typical price: $5-50 for common specimens, $100+ for large or rare articulated fossils

Where rockhounds find echinoid

Classic worldwide localities

England
France
Morocco
USA
Germany

Field-hunting tip

Look in sedimentary rocks like limestone and chalk country, the host setting where echinoid typically forms. If you start seeing calcite, quartz, pyrite in float, you are in the right ground. Field specimens usually show a test (the hard shell or skeleton of the echinoid) habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify echinoid?+

Mohs hardness is 3-4. It typically shows a dull luster. The streak is white. Common colors include white, gray, tan, brown.

Where is echinoid found?+

Notable localities include England; France; Morocco; USA; Germany.

How much is echinoid worth?+

Typical asking prices fall in the range of $5-50 for common specimens, $100+ for large or rare articulated fossils. Quality, size, and provenance can move individual specimens well outside that range.

What minerals are found with echinoid?+

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

What kind of rock does echinoid form in?+

Echinoid typically forms in sedimentary rocks like limestone and chalk. Working float back to the host body is the standard way to chase a fresh occurrence.

What is echinoid used for?+

Echinoid is used in collector, decorative, educational.

Find echinoid on the map

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