Fossil Puzzle 

A skull? Guess again! The answer:


Humans are chordates, with internal skeletons made of calcium. Insects belong to the phylum of arthropoda, and have exoskeletons made of chitin. Both are bilaterally symmetric -- meaning each half is a rough mirror image of the other.

But starfish, sand dollars and sea urchins are echinoderms -- animals designed around a five-sided box made of calcite -- a breed that dates back to the pre-cambrian era, where animal body plans started to first take shape.

The crinoids may look a bit like starfish on a stem, with their mobile arms gathering food and pushing it toward the mouth. Can imagine a sea-urchin on a stem -- a filter-feeder shaped like a hickory nut?

Meet the blastoid -- or "sea bud."



Instead of muscles, echinoderms use a system of tubes pressured by water, creating slow but powerful hydraulic movements. Their nervous system has no centralized brain, but starfish are covered with light sensors that enable to recognize their location and show directed movements. They can also quickly become rigid and immobile when threatened.

Many echinoderms are carnivorous -- hunters that depend upon other animals for their food.

Strangest of all, their growth from a fertilized egg follows a deuterosome pathway-- unlike insects -- placing them surprisingly close to our own evolutionary line.

The last Blastoid vanished in the Permian Extinction, but their fossils remain as tangible evidence of the amazing journey life has taken over the last half-billion years.

Special thanks to Betty Claymore for her help identifying this fossil!




Crinoid Branch

The Blastoid Pentremites from Glen Dean, Kentucky,