Fossil Identifier — What Fossil Is This?
Found something that looks like it was once alive? Upload a photo and our fossil identifier names the most likely fossil type in seconds, tells you how confident it is, and shows you how to confirm it — including whether it's real.
How to get an accurate fossil ID
- • Show the whole specimen plus a close-up of the detail — ribs, sutures, serrations or surface texture.
- • Include something for scale (a coin or ruler); size helps separate look-alikes.
- • Photograph the surrounding rock (matrix) too — it's a strong clue to the fossil's age and type.
- • Shoot in even daylight from a couple of angles so raised and recessed features read clearly.
Fossils our identifier recognizes
Common finds across the major groups — including ammonites, trilobites and shark teeth, plus shells, corals, crinoids, brachiopods and petrified wood. Each entity links to an in-depth field-guide page covering age, varieties and how to spot replicas.
Common fossils identification chart
Most finds belong to a dozen or so groups. Match the overall shape first, then check the one feature that separates it from its look-alikes:
| Fossil | What it looks like | The tell | Age |
|---|---|---|---|
| Brachiopod | A small two-shelled fossil, often ribbed, fingernail- to coin-sized | The two shells differ in size, but each one is symmetrical left to right | Cambrian onward; most common in Paleozoic rocks |
| Clam (bivalve) | A two-shelled fossil, often with fine growth lines | The two shells are mirror images of each other — the opposite of a brachiopod | Cambrian to today |
| Snail (gastropod) | A single shell coiled into a spire | Coils upward like a corkscrew, with no chambers inside | Cambrian to today |
| Crinoid | Small round or star-shaped disks, often stacked into stems | Each disk has a hole through its center — the classic “Indian bead” | Ordovician onward; most common in Paleozoic rocks |
| Coral | A horn-shaped cone, or a honeycomb of small cells | Thin walls radiate inside each cell; Michigan’s Petoskey stone is a colonial coral | Ordovician to today |
| Trilobite | A segmented, bug-like body with a head shield and tail | Three lobes run from head to tail — the source of the name | Cambrian to Permian only (about 521–252 million years ago) |
| Ammonite | A flat, tightly coiled shell, often ribbed | Wavy, frilly suture lines where the inner chamber walls met the shell | Devonian to Cretaceous; died out with the dinosaurs |
| Belemnite | A bullet-shaped stone, often translucent brown or amber | Solid and pointed, made of calcite, with a hollow at the wide end | Jurassic to Cretaceous |
| Orthoceras | A straight cone split into chambers, often polished in black rock | Straight rather than coiled — a squid relative that grew in a line | Ordovician to Silurian |
| Shark tooth | A triangular, glossy tooth in black, gray or brown | Shiny enamel crown over a duller root; minerals color it — modern teeth are white | Most finds are Cretaceous or younger |
| Petrified wood | A heavy stone log or chunk showing bark and grain | Growth rings and wood grain preserved in stone | Many ages; famous U.S. logs are Triassic, over 200 million years old |
| Plant fossil | A dark leaf or fern print in split shale or an ironstone nodule | A thin carbon film that still shows the veins | Especially common in coal-age (Carboniferous) rocks |
| Coprolite | A rounded, lumpy stone | Fossilized dung — may hold bits of bone or scales | Many ages |
How to identify a fossil you found
Work from the broad group inward — that's how paleontologists narrow it down:
- Name the form first: coiled shell (ammonite/nautilus), segmented body (trilobite), tooth, stem disks (crinoid), fan or branch (coral), or leaf/wood impression.
- Read the structure: ammonites show wavy suture lines; trilobites have a three-lobed body; shark teeth have a crown, root and often serrations.
- Check the matrix & locality: the host rock and where you found it pin down the geological age, which is essential for species-level ID.
- Real vs. replica: look for a mold seam, unnatural weight, and missing matrix (see the FAQ).
Exact species often requires a local museum or fossil group — bring the matrix and the find location.
How to identify a fossil tooth or bone
Teeth are the most common backboned-animal fossils, because enamel is the hardest tissue an animal makes. A fossil tooth usually shows a glossy enamel crown above a duller root, and its color — black, gray, brown or blue-gray — comes from minerals it absorbed while buried; a modern tooth is white. Shark teeth are triangular, often serrated along the edges, with a flat root. Mammal teeth are blockier, with ridges or cusps worn down by chewing.
Fossil bone feels heavier than it looks, because minerals have filled its pores. A broken end often shows a spongy, honeycomb-like interior under a hand lens — the network where marrow and blood vessels once ran — while plain rock is the same all the way through. Note exactly where you found it: the rock layer dates the find, and on U.S. public land, bones and teeth of backboned animals can't be collected without a permit.
Frequently asked questions
Can you identify a fossil from a photo?
Often to the broad type, yes — an ammonite's coiled shell, a shark tooth's shape, a trilobite's segmented body or a crinoid's stem disks are recognizable on sight. Exact species is much harder and usually needs the locality and rock age, so we identify the group, give a confidence score, and tell you what to check.
Is it a real fossil or just a rock?
Look for biological structure that's too regular to be random: repeating chambers, ribs, suture lines, a shell's spiral, symmetry, or the texture of bone or wood. Pseudofossils (dendrites, concretions, flint nodules) can fool the eye — if there's no organic structure, it may just be an interesting rock.
How do I spot a fake or replica fossil?
Replicas — especially of megalodon teeth and trilobites — are common. Tells include a visible mold seam, a too-perfect or too-symmetrical shape, light or 'plasticky' weight, uniform color with no mineral variation, and no surrounding rock matrix. Real fossils usually show wear, repair, or matrix on the back.
Is there a free app to identify fossils?
Yes. Our Android app on Google Play is free to download and identifies fossils with the same engine as this page; on iPhone, use this page in Safari. For the best result, photograph the fossil still in its surrounding rock.
Is the fossil identifier free?
Yes — your first 3 identifications are free. Pro covers 100 identifications a day (600 a month), plus value, authenticity and care reports.
Turned out to be a plain rock? Try the rock identifier or browse the field guide