Grace knocks back at the hex wall and investigates its varied tiles, suspecting material tests against his air. He spots a single clear hex and, peering through, sees a three‑fingered hand. The alien taps and uses miniature models of Grace’s suit and ship to signal him to return inside, which he does.

Robotic arms on the Blip‑A remove the hex wall and work in darkness, implying a vacuum and different vision. After another knock, Grace enters the tunnel to find a full clear barrier and beholds the alien—pentagonal, five‑limbed, rock‑skinned, and clothed—who he dubs Rocky. Rocky communicates with audible chords and gestures.

Rocky leaves two embossed spheres containing bead constructions. Grace deciphers them as molecule models: his sphere holds O2; Rocky’s holds many NH3 molecules. The ratio implies Rocky’s environment is ~29 times higher pressure, demonstrating why a barrier is needed and highlighting xenonite’s strength. They continue with pantomime due to incompatible atmospheres.

Exhausted, Grace shows an analog clock and marks a two‑hour return time. Rocky insists the clock be fixed to the barrier, then presents an Eridian clock with rotating raised symbols. Observing it, Grace infers base‑six numerals and measures an Eridian second by timing the rotors.

Grace calculates 1 Eridian second ≈ 2.366 Earth seconds, establishing a shared time unit. He marks his clock for a short break, waves goodbye, and goes to nap, resolved to build a common scientific vocabulary before tackling Astrophage.