This is a small nature journal entry that moves from deep time to a few feet from the speaker's door. The short verse sections catch quick moments of attention: an ancient seabed, a sudden roar from a quarry, the first cicada of the season, a slug that seems to mark the day like the shadow-pointer of a sundial. The speaker wonders which tree will serve as "today's gnomon," as if the whole landscape were a clock to be read.
The prose ending shifts to a lighter, funnier tone. Excited to find coral fungi so close to home, the speaker asks why he never comes back here, then stands up and sees the poison ivy. The joke lands because the answer was there all along. The mood is curious, observant, and gently humorous. It celebrates noticing small things, while admitting that our own backyards can hold both wonder and a good reason to stay away.