Common Fossils: Echinoids

Let’s talk about one of our all time favorite fossils, Echinoid fossils. These common but highly collectible specimens are also known as fossilized sea urchins.

Echinoid fossils are not only fascinating, they can be an affordable way to start your fossil collection. These beautiful fossils are often polished to give them a nice shine and to showcase their aesthetically pleasing structure. These fossils are a great addition to any collection and can sometimes be found in our mineral boxes.

Echinoid fossil visiting La Jolla Shores in San Diego.

When is the earliest recorded sea urchin known to date?

The earliest Echinoid fossils date back to 450 million years ago during the Ordovician Period and can be found all over the world. Echinoids are still around today and are common in costal environments.


Is there a reason why Echinoids have 5-fold symmetry?

Yes! Echinoids, or sea urchins, are closely related to sea stars and share this common trait.

Where did the urchin’s spines go?

The fragile spines of these creatures are usually not preserved during the fossilization process but we do get these nice cushion shaped specimens that show much of the organism’s body structure.

What kind of rock are these fossils typically found in?

Echinoid fossils are often found in marine deposits from the mid to late Mesozoic—the golden age of the dinosaurs!

Echinoid fossil laying next to a piece of California Kelp.