This week’s cute little fossil takes us back to the Permian Period, around 250–300 million years ago to meet something nicknamed "sea buds": Deltoblastus!
At first glance, these fossils often get mistaken for shells or strange pebbles, but Deltoblastus was actually a blastoid — an extinct group of echinoderms, distant relatives of starfish, sea urchins, and crinoids.
While blastoids and crinoids look quite similar, they had some key differences. Crinoids (the “sea lilies”) typically had long, distinct, feathery arms for feeding. Blastoids, on the other hand, had a more compact, bud-shaped body, with their food-gathering structures tucked in close and filtering food up grooves towards the mouth at the top.
What we usually find fossilised is the hard, plated “bud” (called a theca), made up of tightly fitted calcite plates arranged in a wonderfully geometric pattern. Nature really does provide some fascinatingly architectural designs!
This week’s sketch shows that classic blastoid theca, or “bud”, compact, elegant, geometric, and with its mouth right next to… well, you can see it in the picture!
Blastoids thrived for millions of years before disappearing at the end of the Permian, during the largest mass extinction Earth has ever seen, the event known as “The Great Dying.”
Fun fact: The name Deltoblastus comes from the triangular (“delta”) shape formed by some of its plate patterns. It’s a relatively tiny fossil with surprisingly precise symmetry.
