The composition of this SU suggests hydraulic concrete, and its presence on the walls and floor clearly suggests some kind of activity involving liquid. The circular rough patch and associated "channel" suggest that this space was used as a press for wine or oil, though some elements of the press are missing. The circular area presumably sat beneath a stone bed for the press, pressure from which might explain the rough surface. Similarly, perhaps the channel was once built with stone, ceramic, or even wooden elements which are now missing, possibly spoliated.