Not every sea creature needs to hunt for its meal. Filter feeders passively intake plankton and other small creatures with a special feeding organ. Most of these creatures are stationary animals anchored to the ocean floor, but one incredible animal takes its filter feeding to go: the graptolite. First appearing during the Cambrian Explosion, graptolites soon evolved the ability to float along the ocean's current, living in sprawling colonies of polyps. Because of their large distribution, graptolites are excellent (not to mention beautiful) index fossils.

These graptolite specimens, which we've titled Wenlockian Spiral Graptolites, show the organic tubaria that hosted the polyp colonies. In a way, these very fossils are striking evidence of these creatures' unique evolutionary pattern.

These graptolite specimens date to the Wenlock Epoch of the Silurian Period, 433.4-427.4 million years ago. They were found near Bardo, Poland along the Sudetes Mountains.

Each specimen has been individually photographed and listed by size and all of them come complete with an informational card that serves as our statement of authenticity. You can explore all the specimens in the collection below!

Graptolites are a group of aquatic animals a part of the hemichordates phylum; they are anatomically similar to their cousins, the still living pterobranchs, worm-like creatures that are tethered to the ocean floor. Graptolites first appear in the Cambrian Explosion’s fossil beds, persisting into the Carboniferous Period before largely dying off. Across that time, they evolved from mostly benthic groups like the dendroids that were tethered to the ocean floor, to the free-moving planktonic graptoloids that moved with the currents.

From there, graptolites spread across the world’s oceans, propelled by natural currents or perhaps swimming themselves with their tentacles. Their forms changed into a conic structure to better navigate the waters, with long tubes called tubaria that hosted the actual colonies of graptolite polyps. The widespread distribution of graptolites makes them useful index fossils, revealing much about the environment they lived in.

At sites in Eastern Europe, graptolites show evidence of periodic oxygen crises, as graptolites flourished in warmer, oxygen-deprived waters but died out suddenly in cooler, oxygen-rich waters, leaving a neat record of the die-offs. Without graptolites, scientists would be ignorant of these periodic oxygen crises during the Silurian Period.

One can also see how graptolites weathered these extinctions, as new species would soon evolve to replace those that had died in a process called adaptive radiation, while others would naturally move into the location, carried by the ocean current. This evolutionary cycle could only persist for so long though, and many graptolite species were wiped out in the Kozlowskii extinction event.

The “graptolite fossils” discovered today are not the full bodies of the organisms. In fact, they are organic tubaria built by polyp colonies, while the actual soft-bodied graptolites were not preserved during the fossilization process. Like many creatures, these fossils only capture a fraction of the elegance of the animals in life, polyp colonies living on a bustling network of tubes that flowed through the ocean.

As advantageous as this form was, it was likely their undoing as they became more at risk to changes in the ocean’s oxygen and mineral levels. The still living graptolites are primarily the benthic forms which remained attached onto the sea floor rather than float like plankton.