Do certain things catch your eye as you wander through the woods? I get drawn to things like: different colors, different shapes, things that seem out of place, odd looking things.
When I saw this Red Pine stump I had to check it out. What made it this way?
Sap wood (outer area of the tree trunk that transports material up and down the tree) may rot at a different rate than heart wood (area of wood at the center of the tree trunk). The heart wood rotted away while the sap wood lasted longer. The branch stubs sticking in towards the center of the stump are denser and so they remained after the heart wood rotted away.
Trees grow at different rates depending on the time of year. That is what creates the growth rings in trees like the Hemlock below. Fast growing spring wood is the wider less dense growth ring in a tree trunk. As the growth slows down in the winter the ring is denser and thinner. Less dense wood tends to rot faster than dense wood.
Not every part of a tree grows at the same rate. For example, shaded branches grow slower than those up in the canopy, where the sun can easily reach them providing light energy for faster growth. This differential rate of growth creates denser and less dense wood. That leads to different rotting rates: Less dense wood rotting quicker than dense wood.
Can you guess another factor in rotting rates? How about the amount of moisture? The wetter the conditions, the faster the rotting occurs as long as the tree is not under water. Downed trees that lay on the ground or the parts of them touching the ground tend to rot faster. Check out these shapes and texture due to differential wood rotting:
Now it is your turn to explore and see what rotten gems you can come up with. Older softwoods (trees with needles) or conifers seem to create the most variety, but any woods can do. You never know what you might find till you get out and explore. So, protect yourself from ticks and see what you can find. If you come upon something interesting, then post a picture on the MyWoodlot forum so we all can enjoy it.