Hi - we just chopped down 2 hickory trees (the previous homeowners planted them RIGHT next to our house... less than 10 ft away) so we have a ton of wood! They were very healthy, nut-producing trees (believe they were shagbark). We noticed as we were chopping the sections into logs that they had these odd black spots in the rings. These were found the same day the tree was cut down. What are these spots, and is it safe to still smoke with the wood? I’m attaching pictures.