This is a clock. It is marking the slow demise of an old poplar.
Many of the trees in our woods sport visible signs of inner decay and rot — firm, bracket-shaped fungi growing on their trunks.
Some tree fungi live only one season. This one is a perennial, adding new “rings” each year. It will continue to do this even after the tree has died.
The “shelves” or brackets are the fruiting part of the plant, producing air-borne spores some of which may infect other trees. The main part of the fungus is invisible. The “roots” (mycelia) grow throughout the inside of the tree. Fungi can’t produce their own food but rely instead on the energy stored in plants that do, like trees.
These fungi are vital to a healthy forest. They break down dying and dead trees, recycling the nutrients and minerals back into the soil to be used, perhaps, by new trees. This dissolution may take decades or a century or more.
A sign of time.