I'm getting better with plants, but I haven't really found anything that says seed or spore pod to me. This one finally does. It's a small depression with texture. I wish I had the other side, but I didn't see it. This was from a layer with many ferns, Calamites, and Cordaites. Concretions are about non-existent here. In fact, there may be none at all. It's the texture in the depression that has me thinking seed pod mold.