Some thoughts about keystone and some info acquired:
Stone of Jacob
https:// en.wikipedia.org/wiki/Stone_of_Jacob
20 facts revealed about the Stone of Destiny
https:// www.historicenvironment.scot/about-us/news/20-facts-revealed-about-the-stone-of-destiny/
The Stone of Destiny and the end of the New World Order
https:// mtrial.org/030409-stone-destiny-and-end-new-world-order
Masonry and it's symbols.
https:// books.google.com/books?id=S3BXsFJ5aZYC&pg=PA690&lpg=PA690&dq=is+stone+of+destiny+the+keystone&source=bl&ots=a-cAblKZ0I&sig=aCDJLLBI_sty_cXc_MCbTt-u23U&hl=en&sa=X&ved=2ahUKEwixgrrRlMjfAhVzNH0KHR9fBfE4ChDoATAAegQIChAB#v=onepage&q=is%20stone%20of%20destiny%20the%20keystone&f=false