I worked a while at a commercial mill. We had the biggest white oak trunk come in I ever saw in the mill, so big the debarker couldn't flip it onto the chain line, had to push it with a loader.
Circle saw took a cut, the we had to finish it with a chainsaw. Flipped it 90 degrees and another cut, and finished with the chainsaw to get 2nd slab off. Two more times then the sawyer started cutting 8/4 off the huge cant.
Then the saw just stopped (300 HP 440 volt 3 phase), lights in the mill dimmed. Carriage would not back out of the cant. We had to get all the guys at the mill to take a log and battering ram the carriage back from the saw. The circular blade was badly damaged, warped like a potato chip and carbide teeth snapped off.
Turns out it was a "line tree". At some point it supported a split rail gate, that was held with 5 horse shoes ground to points, and driven into the tree. The tree grew around those many years before.
The owner was pissed at their loggers who bought the tree in, and they admitted to it being a "line tree". Mill was shut down most of the day when they changed out the saw blade. We were happy as it was ~ 95 oF and we got a paid break all afternoon. We just did clean up instead of stacking 8/4 oak.......