Blastoids are an extinct group of stalked echinoderms known for their distinct bud-like shape, often featuring five-fold radial symmetry similar to a flower bud. Collectors typically look for the 'calyx,' the main body portion, which is commonly found in Paleozoic-aged limestone deposits. They are frequently found in marine sedimentary rocks and are highly prized by amateur paleontologists for their aesthetic beauty and precise symmetry.

fossilcommon

Blastoid

Is this blastoid?

3-step field check

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

1
Name the organism
Decide what left the fossil before worrying about the rock. Organism: Extinct stemmed echinoderms (class Blastoidea). Age: Ordovician to the end of the Permian; most diverse in the Mississippian.
2
Check the preservation
Preservation: Interlocking calcium carbonate plates. That controls the weight, the hardness and how the piece takes a polish.
3
Match the color range
Compare against the expected color range: gray, brown, white, tan.

Often confused with

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

Often found alongside blastoid

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

All properties

Colors: Gray Brown White Tan
Rarity: Common
Uses: Collector, Decorative
Host rock: limestone
Organism: Extinct stemmed echinoderms (class Blastoidea)
Age: Ordovician to the end of the Permian; most diverse in the Mississippian
Preservation: Interlocking calcium carbonate plates

Where rockhounds find blastoid

1 mapped spots

Classic worldwide localities

Kentucky
Indiana
Illinois
Tennessee
United Kingdom

Field-hunting tip

Where it forms: limestone. If you start seeing calcite, quartz, pyrite in float, you are in the right ground. In the U.S., the densest reported localities are in Michigan. Start trip planning there.

Browse 1 U.S. spots for blastoid →

Common questions

Where is blastoid found?+

Notable localities include Kentucky; Indiana; Illinois; Tennessee; United Kingdom.

Can I find blastoid in the United States?+

RockHoundR maps 1 blastoid rockhounding spots across 1 U.S. states. The top states are Michigan.

What rocks look like blastoid?+

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

What minerals are found with blastoid?+

Blastoid 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 blastoid form in?+

Where it forms: limestone. Working float back to the host body is the standard way to chase a fresh occurrence.

What is blastoid used for?+

Blastoid is used in collector, decorative.

Find blastoid on the map

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