"X" stands for Aton and also for the biblical hero Nimrod, known as the "mighty hunter of Jehovah" http://www.irishoriginsofcivilization.com/irishoriginsexcerpts/book2_chap41.html
Pharaoh Akhenaten and his family adoring the Aten, second from the left is Meritaten who was the daughter of Akhenaten.
Relief dated 1350BC of the sun disk of Aten
Aten was depicted as a Sun disk with rays reaching to the earth. At the end of the rays were human hands which often extended the Ankh to the Pharaoh. Aten was called the creator of man and the nurturing spirit of the world. Aten was solely worshipped by Pharoah Akhenaten (Amenhotep IV) and his first wife Nefertiti and this caused much discord in the kingdom. (see Akhenaten above) Akhenaten's successors did all they could to erase Akhenaten and his beloved Aten from the public eye. Eventually, Akhenaten became abandoned and the name "Akhenaten" was called a "heretic king." http://www.magialuna.net/dieties.html
The emblem of the Grand Lodge of the Order of Malta, featuring two Masonic columns representing the sacred trees of ancient Druidry, and the pyramid with solar rays at the top. The eye of Aton within the pyramid can be seen on the American one-dollars note. http://www.irishoriginsofcivilization.com/appendices/druidicsymbolism.html
The mural on the Grand Lodge of Massachusetts, the headquarters of American Masonry. Note the hammer and rule (a stylized "G"), and the Atonist solar rays. http://www.irishoriginsofcivilization.com/appendices/druidicsymbolism.html