A thread that coarse is almost certainly not a fastener of any kind…it would never stay tight. It appears to be the worm part of a worm drive. I can’t think of a single reason why a toilet would have such. Oscillating lawn sprinklers, garage door openers I can see.
I’m going with the “somthin’ a fool kid done” theory myself.
Well, that’s good to know. If it had indeed fallen out of the fill tube, I am sure someone would have recognized it. My wife was dismantling everything in the room prior to painting, and although I cannot imagine it did not come from the toilet, I am begining to think I am wrong. My thoughts were predicated on the fact that it appeared on the plastic on which I placed the toilet and was not seen until after it was moved. If I ever figure out what it is and where it came from I will let everyone know. Should be a few weeks.
No, I never did figure it out. I reinstalled the toilet without it and it has been working just fine ever since. I guess it was just something perhaps under the toilet left over from construction. I just don’t know.