Full photo here.
It's the floor of a mud brick structure at Kom el-Hisn in the Delta, Old Kingdom.
The room was sectioned in half so these are the only features like this present. They are hard-packed clay and are about 40-50 cm square. I've been sorta calling them column bases, but they seem rather close together for that. There was little in this room to suggest any function for the place either. There are at least 6.