This sliver of maple wood cut from a tree that fell over the Red Rectangle Trail looks like a map of some unfamiliar world so I was surprised to learn that it is exactly that. The squiggly black lines superimposed on the circular growth rings look like meandering rivers. Known as zone lines, they mark territorial boundaries between species of fungi competing for the dead wood. I felt a little sad to learn about this self-serving behavior of micro-organisms. The sadness made me realize that, even though I swear I never thought about it, I had assumed that fungi would share.