Very thin wall abutting 8340, forming a basin-like structure in Room I-20. Wall is only just visible, abutting the floor prep to the south, and still filled by a post-abandonment deposit as of end of season 2018. Appears to be composed of somewhat regularized tufo stones, of slightly different sizes, mortared together with a gray mortar. The facing on the north side appears more regularized that in the nearby walls 8396 and 8398. Notably, a very small layer of signinum is preserved at the western limit of this wall (on its northern face), which continues north along wall SU 8340 and also abuts wall SU 8396. This signinum has not been fully exposed and lacks a separate SU as of end of season 2018.