The SU is two stones that act as leveling for the corner block of wall 2245 and might represent a later act to level the block, if it were collapsing for some reason. During post-excavation study, this feature was reinterpreted as a possible fragment of the east-west running wall 2239, that continues in a fragmentary form with SU 2396 to the west.
The SU is a later wall socle/reparation.
Two basalt stones beneath corner block of walls 2239 and 2245 in room C1