I found some pictures from 2003 that I took at the Museum of Oriental Antiquities, a part of the Archaeological Museum complex. I was żnformed this is a limestone Sumerian tablet, with its bronze (?) nail. Quite a few Sumerian tablets (mostly clay) and objects which were excavated from southern Iraq made their way into the Imperial Ottoman Museum in the 19th century. The Istanbul Archaeological Museum (as it is known today) houses a wonderfully rich archive of Sumerian texts, many of which were published by Muazzez Ilmiye Cig.

Thanks for letting us know.