Well that is different ain’t it. Looks like small cracks that accepted “whatever” over time. Possibly organic soil from above, possibly below. Still might make nice lathe projects.
I see oak like that all the time. Those are cracks and you can almost just let the maul fall on them and they split right up. It's really wet where it's black.
I found this downstairs in the woodpile this evening that was split two years ago. You can see where it split right at the dark areas. When it's freshly split if you look closely you can sometimes see little white worms crawling around. You can also see it turns green once it dries.
