Last weekend (August 23-25), I went to upstate New York to visit some friends. On the way back, we stopped to look for fossils in a couple of places. One place that we went to was Schoharie, NY; we hadn't been there before. When we got there, this is what we saw:
It looked pretty uninteresting at first, but when we started picking up rocks and looking at them, it turned out that nearly every rock had a fossil! You see, this part of New York was covered by an ocean 420 million years ago, and today's rocks were ocean mud at that time. The fossils that we found included a lot of brachiopods, like this:
Brachiopods are bilaterally symmetrical; molluscs like clams and oysters are not. There are a few modern species of brachiopods, but they used to be much more common.
In addition to brachiopods, we found fossil crinoids, or sea lilies, which are related to echinoderms like starfish, and molluscs like clams. It seemed that every chunk of rock that we picked up was covered in shells and bits of crinoids and coral.