KNM-ER 6128 is a right upper premolar, probably P³ classified, as from a Paranthropus boisei. There is some damage to the tips of the cusps, but this appears to be post-mortem. The roots are nearly fully developed but not quite closed, and it is likely that this tooth was in the process of erupting [1]. It was found in Area 104 of Koobi Fora, 4m below the A2 marker and is dated to ~1.78 Ma [2][3].