 Each of the 544 11✕11" masonite tiles represents 1 million years, encompassing the last 544 million years of history, from the Cambrian Explosion to the present day.Each tile features life-size images of fossils from its respective interval of time, both two-dimensional and in low bas-relief, displayed on a background representing the common rocks and sediments of the time.The images are based on actual specimens from PRI's collections.