The SU is a single large ashlar block, clearly associated with an earlier phase of habitation in this sector. At this point the original function is unclear, although it was clearly later incorporated into the substructure of the floor in this area of the courtyard. It is possibly associated with the same phase as block 2436. During post-excavation study, this feature was reinterpreted as a possible piece of the original Phase 1b Space 7 paving associated with SU 2436. This block's different position might be due to its reuse as foundation for the later Phase 2 cocciopesto floors.

The SU is a stone block underneath floor preparation 2272.