Nemoto has a line of dialogue (page 498 in my edition):
Because they were lonely. The Old Ones were the first sentient species in their universe. They survived the crises of immaturity. And they went on, to walk on the planets, to touch the stars. But everywhere they went - though perhaps they found life - they found no sign of mind, save for themselves.
I think there was another, similar, reference to "mind" as well, which also sounded very similar to a passage in 2001
In addition, the fact that the Red Moon was for all intents an purposes an incomprehensible artifact that took people between universes in the Manifold struck me as just another kind of Monolith.
Now I'm wondering whether the Manifold series was written before or after Baxter's collaboration with Clarke.