If you look near the bottom, you can see where the tablet has been edited by having a section of cunieform chiseled out (the small rectangle second from left and second from bottom)
"Cuneiform script is one of the earliest known forms of written expression. Emerging in Sumer around the 30th century BC, with predecessors reaching into the late 4th millennium (the Uruk IV period), cuneiform writing began as a system of pictographs. In the course of the 3rd millennium BC the pictorial representations became simplified and more abstract. The number of characters in use also grew gradually smaller, from about 1,000 unique characters in the Early Bronze Age to about 400 unique characters in Late Bronze Age (Hittite cuneiform). Cuneiform writing was gradually replaced by alphabetic writing in the Iron Age Neo-Assyrian Empire and was practically extinct by the beginning of the Common Era. It was deciphered from scratch in 19th century scholarship.
Cuneiform documents were written on clay tablets, by means of a blunt reed for a stylus. The impressions left by the stylus were wedge shaped, thus giving rise to the name cuneiform ("wedge shaped," from the Latin cuneus, meaning "wedge").
The Sumerian script was adapted for the writing of the Akkadian, Eblaite, Elamite, Hittite, Luwian, Hattic, Hurrian, and Urartian languages, and it inspired the Ugaritic and Old Persian national alphabets."