One episode had a second Triforce, so if you could assemble both you'd have a Hexaforce. Maybe. They're getting there.

Wouldn't that just be a soccer ball?

It's a pretty obvious graphic pattern. It wouldn't be crazy to think that it would have been developed independently of any influence.

Still what you mention looks dead on

Hojo Clan Wiki

Every time you roll this die for SAN loss you have to roll this die for SAN loss

It would be a cool thing to do a 3-D copy of.

Yeah, sometimes they apply a clear (removable) coating to the surface first and then write on it.

Other times it's just low-acid inks (or extremely soft-graphite pencil) applied directly to the surface. It's only painted objects that they really can't do that with.

Ultimately, it adds to the provenance, so it's easier to track and verify many years from now. It's different than some kid finding it on the playground, and etching his initials in it with a protractor.