SU comprised largely of limestone and a mix of mortar and lime irregularly deposited throughout the sides and base of the basin (8184). Given this, alongside occasional small inclusions of ash, it seems likely this basin was used, at least in its last phase, for the production of mortar. This mortared deposit is, in fact, largely indistinguishable from the sides of the basin; the basin itself may thus have been created ad hoc as mortar was mixed, regularized only in a limited way at the upper corners.