Lines

After a long break I finally had a walk with my friend A. and her dog Tico.
I couldn't take Caspar with us, because Tico gets very agressieve against Caspar. That's really a pity, because I used to walk with her weekly for years with Omo and Blue. It was great to catch up and we will walk again soon.
On our way we passed this left over trunk. I've never seen such carved lines .in a tree stump. I guess it is so that the tree stump rots faster.
Any other ideas?

My mystery macro was indeed the seeds of a yellow pepper.  :-D