Sarah, One of my favorites was in the paleontologic teaching collection at Stanford University. It was just a clam, preserved in sandstone with both valves still attached and gaping a little. When you opened the valves, which had been broken apart, there was a leaf inside. Naturally, our assignment was to explain how the leaf and clam could both be preserved in one place. The students also wondered, Was this a herbivorous clam? Or a clamivorous leaf? Andrew K. Rindsberg Geological Survey of Alabama