ALSO KNOWN AS THE SUN STONE AND CALLED TONALMACHIOTL IN NAHUATL.   TONALMACHIOTL, FROM TONALI-ENERGY AND MACHIOTL-MODEL OR MOLD, IS A MASSIVE SCULPTURE THAT COMBINES MANY ANCIENT ASTRONMICAL CALENDARS INTO ONE BEAUTIFUL WORK OF SCIENCE AND ART. 

THE MOST COMMON INTERPRETATION HOLDS THAT AT THE CENTER RESIDES TONATIUH, THE SUN.   DUE THE STRIKING RESEMBLANCE TO A STONE GLYPH OF TONACATECUHTLI, OTHERS BELIEVE THAT DEPICTED IN THE CENTER IS THE MALE REPRESENTATION OF THE EARTH.  IN ANY CASE, SURROUNDING THE CENTRAL FACE IS THE NAUI OLIN SYMBOL.   WITHIN EACH CORNER IS ONE OF THE FOUR PREVIOUS WORLDS OF THE AZTECA/MEXIKA CREATION STORY.  THE TONALMACHIOTL ITSELF REPRESENTS THE CYCLE OF THE FIFTH SUN.  THE FIRST CIRCLE IS THE 20 SYMBOLS OF THE TONALPOUALLI, OR SACRED 260 DAY "RITUAL" CALENDAR.  TONALPOUALLI IS DERIVED FROM TONALI-ENERGY AND POUALI-COUNT AND TRANSLATES AS "THE COUNT OF THE ENERGY OF THE DAYS."  THE TONALPOUALLI APPROXIMATES THE GESTATION PERIOD OF A HUMAN CHILD  AND IS AN ASTROLOGICAL CALENDAR THAT WAS USED  TO NAME NEWBORN CHILDREN. 

THE TONALMACHIOTL ALSO CONTAINS THE CYCLES OF THE MOON AND THE PLANET VENUS.  EACH HALF OF THE OUTERMOST RING REPRESENTS THE SACRED 52 YEAR CENTURY AND TOGETHER FORM A 104 YEAR LONG COUNT.   THE TWO XIUHKOATL, OR FIRE SERPENTS, AT THE BOTTOM WEAR THE FACES OF KETZALKOATL AND TEZCATLIPOKA AND SYMBOLIZE OMETEOTL.  THE SEVEN STARS ON THE HORNS OF THE SERPENTS REPRESENT THE PLEIADES CONSTELLATION.  AT THE TOP OF THE CALENDAR IS THE DATE 13 AKATL, OR 13 REED, THE DATE WHEN THE CALENDAR WAS COMPLETED