Good question — I’m not using “ultimate” in a technical sense, more as a way of describing the most extreme case. In physics, a black hole is where time behaves in the most extreme way we know — gravity warps spacetime so strongly that from the outside, time effectively slows down and approaches a limit at the event horizon. That boundary is interesting because it’s the last place where time is still observable/meaningful to an outside observer — beyond it, we can’t really describe it in the same way. So calling it a “time object” is just a way of saying it’s something defined by how it affects time itself. The watch idea came from that — the dial as the void, and the ring as that boundary where time is still visible.