Board Thread:Theories and Speculation/@comment-24824859-20150704165201/@comment-734582-20150706073350

I would say that a Six Paths user has a set amount of Truthseeking Balls they can call upon but are limited to that amount and once destroyed can not be recreated. This seems to be a limit in volume (all balls are equal in size) of Truthseeking matter. I'm pretty sure this is the topic at hand: why madara, Obito and Naruto couldn't create more TSB's.

The only exception to this is Kaguya who could create a massive TruthSeeking ball and it far exceeded the volume of the other TSB's. So it stands to reason that the (unlimited) TSB creation jutsu is a kekkei Mora.