Rocky

Name

• Canonical: Rocky (a nickname Grace gave him because the alien's body looks armored, like rough stone)
• True Eridian name: Rendered in the text as a sequence of musical chords; not pronounceable in human speech. We use "Rocky" throughout.

Role in the story

An Eridian engineer; the sole survivor of a 23-member crew sent from his home planet Erid (in the 40 Eridani system) to Tau Ceti for the same reason Grace was sent there — their star is dying of Astrophage. He becomes Grace's working partner, intellectual peer, and the deepest friendship in either character's life. Eridians are, by Erid's standards, a working culture of relentless engineers; Rocky reverse-engineers everything he touches and treats Grace's primitive Earth tech with reverent enthusiasm.

Personality / energy

Generous, curious, instantly loyal, and emotionally direct in a way Grace finds disarming. Rocky has no concept of irony but a deep, dry humor of his own. He grieves openly. He builds for friendship as readily as he builds for survival. His engineering instinct is "if it's broken, find a material and start fabricating" — Eridian fabrication tech is centuries ahead of human in materials science but oddly behind in computing. The novel's emotional engine is his and Grace's friendship.

Physical description

Rocky's body is described in the text in considerable detail and we should render him consistently across every appearance. Lock these specs:

• Body plan: five legs (not six, not eight) splayed in radial symmetry around a central body
• Size: roughly the size of a large dog or a Labrador in Earth-pressure scaling — small enough that Grace can lift him; not human-scaled
• Carapace: rocky, segmented, dull gray-brown plates that look like stone or rough armor — hence "Rocky." Subtle warmer brown undertones.
• No eyes: Eridians "see" via passive sonar (high-frequency clicks and echo). The face/head area has no eye sockets, no visible visual organs.
• Mouth and manipulators: clustered on the underside of the central body; the manipulator pincers are precise, tool-using engineering implements with multiple finger-equivalents
• Vents: a series of small slits along the carapace — the Eridian equivalent of breathing apertures, processing ammonia
• No face in the human sense: he is more like an articulated armored creature with intent than a humanoid alien
• "Pentaradial" — five-fold symmetry, not bilateral

Outfit / clothing notes

Eridians do not wear clothes the way humans do, but Rocky operates inside an engineered xenonite life-support sphere whenever he is in the Hail Mary. The sphere is a key visual element:

• Transparent or near-transparent xenonite, slightly amber-tinted
• Roughly 1.2–1.5m diameter — Rocky inside it like a small armored creature in a glass globe
• Pressurized to ~29 atm with ammonia atmosphere — the interior glow is a warm amber-orange
• Manipulator gloves built into the sphere wall so Rocky can interact with the outside world
• Equipped with grip handles, a small tool rack inside, and tiny interior lights

Visual motifs (recurring objects, color associations, symbols)

• The xenonite sphere — Rocky's near-permanent visual frame
• The hex-wall / honeycomb pattern — present in every Tube scene
• Warm amber-orange light against deep black (echoes the cover's gold-on-black DNA in the literal shape of his ammonia atmosphere)
• Small carved Eridian gift-objects — Rocky carves friendship tokens
• Tap-rhythms on a transparent surface — his hand-language to Grace

Magic / power signature

None — Rocky has no superpowers. His "signature" is engineering capability that looks like magic to humans: rapidly fabricating xenonite, building entire structures from raw materials in hours, repairing things by hand at speed. Render as: Rocky wielding precise tool-tipped manipulators with a quiet, total focus.

Chapter appearances

Chapters 10 (first appearance) through 25 in the present-day arc; in Chapter 30's epilogue he visits Grace in his Erid dome.

Source references

See ../sources.md. Primary references: Wikipedia, LitCharts, SuperSummary, fan wiki cross-checks, TV Tropes.

Confidence

High for body plan, sense modality (sonar), atmosphere (ammonia at high pressure), and his sphere. Medium for exact rendering of the carapace (every reader interpretation differs slightly) — we commit to gray-brown stone-plated armored five-legged silhouette with no eyes and underside manipulators, and use that consistently.