Looks like a knotted string of butt hairs connected across the diameter of the anus, splitting the turd in twain. At some point the pressure of the bowel movement overstressed the butt hair bridge, snapping it and allowing the remainder of the shit to come out as one.
I'm not sure I agree, the diameter of the trunk isn't significantly different from the diameter of the branches. If it were split, the branches should be half as wide.
I think what happened is that the beginning of the turd was the top of the trunk, and it broke where the end of the lower-right branch is. You can see that it broke at an angle. Then the remaining part came out and that angled bit is where the left branch attaches to the trunk. I think it landed there in it's soft/warm state and merged together at that point. You can see that the color of the top of the left branch is the same as the end of the right branch, then transitions to lighter.
And that's as much turd analysis as I want to do today.
This is bringing back memories of not only finding the same thing, but also of the turd that I found in my front flower box one February that was full of cables.
The elusive petrified rabbit(tm) personal massager. Some ancient astronaut theorists believe such technology was beyond what humanity was capable of at the time. The question is: who gave the technology to our ancestors?