This article's name is conjectural. Although this article is based on official information, the actual name of the article's subject is pure conjecture.
Knuckles facing off against the Tunnelbot in Lava Reef Zone Act 1.
Tunnelbot is a robot built by  Dr. Robotnik, that briefly appears at Lava Reef Zone Act 1 in . The robot seems to be a larger variation of the first Sonic & Knuckles Tunnelbot from Marble Garden Zone, with four drill attachments.
The Tunnelbot appears three times in Lava Reef Zone, once in
Sonic's story and twice in Knuckles' story (depending on if the player takes the upper pathway behind the robot). In both stories, when the player faces it in the open area, the robot is about to start the drilling process, which makes the ground below collapse. In Sonic's story, the robot falls into the lava pool, and in Knuckles' story, it attempts the same process but stays on the edge of the upper platform where it remains intact.
Sonic the Hedgehog 3 & Knuckles
Main articles ( Sonic 3, Sonic & Knuckles, Sonic 3 & Knuckles) | Gallery ( Sonic 3, Sonic & Knuckles) | Beta elements | Staff ( Sonic 3, Sonic & Knuckles)
Sonic ( Super Sonic, Hyper Sonic) | Tails ( Super Tails) | Knuckles ( Super Knuckles, Hyper Knuckles) | Dr. Robotnik | Mecha Sonic ( Mecha Sonic's Super State) | Animals ( Flicky ( Flicky's Super State), Pocky, Pecky, Cucky, Ricky, Rocky)
Batbot | Blaster | Blastoid (Carnival Night Zone) | Blastoid (Hydrocity Zone) | Bloominator | Bubbles | Bugernaut | Butterdroid | Catakiller, Jr. | Chainspike | Clamer | Cluckoid | Corkey | Dragonfly | EggRobo | Fireworm | Flybot767 | Hyudoro | Iwamodoki | Jawz | Madmole | Mantis | Mega Chopper | Monkey Dude | Mushmeanie | Orbinaut | Penguinator | Pointdexter | RhinoBot | Ribot | Rock'n | Sandworm | Skorp | Snale Blaster | Spikebonker | Spiker | Star Pointer | TechnoSqueek | Toxomister | Turbo Spiker
Angel Island Zone | Hydrocity Zone | Marble Garden Zone | Carnival Night Zone | IceCap Zone | Launch Base Zone | Special Stages | Bonus Stages
Sonic & Knuckles
Mushroom Hill Zone | Flying Battery Zone | Sandopolis Zone | Lava Reef Zone | Hidden Palace Zone | Sky Sanctuary Zone | Death Egg Zone | The Doomsday Zone | Special Stages | Bonus Stages
Azure Lake Zone | Balloon Park Zone | Chrome Gadget Zone | Desert Palace Zone | Endless Mine Zone
Doctor Robotnik’s Flame Craft (Angel Island Zone Act 1) | Doctor Robotnik’s Whirlpool Machine | Tunnelbot | Self D-Struct Machine | Iceball | Swing’m Spikez | Hei Hou | Gapsule | Barrier Eggman | Guardian | Heat Arms | Egg Mobile-H | Flying Eggman | Red Eye | Death Ball
Doctor Robotnik’s Flame Craft (Angel Island Zone Act 2) | Doctor Robotnik’s Waterspout and Depth Charge Machine | Doctor Robotnik’s Jet Drill Pod | Doctor Robotnik’s Energy Ship | Doctor Robotnik’s Freeze-O-Matic | Ball Shooter | Beam Rocket | Big Arm | Jet Mobile | Hang Mobile | Egg Golem | Hot Mobile | Knuckles | Mecha Sonic | Mecha Sonic's Super State | Kyodai Eggman Robo | The Doomsday Zone
Bound Jump | Double Jump | Fireball Spin Dash | Glide | Gliding Knuckles Attack | Hyper Flash | Insta-Shield | Propeller Flying | Spin Jump | Spin Dash | Spin Attack | Wall Climb
Air Bubbles | Balloon | Banana | Bomb | Booster | Bumper | Bumper wall | Cannon | Capsule | Change | Chaos Emerald | Cloud | Continue | Fan | Jump Stand | Monitor ( Water Shield, Flame Shield, Invincibility, Lightning Shield, Super Ring, Power Sneakers, Extra Life, S, Eggman) | Movable box | Mushroom | Pulley | Ring | Signpost | Self-Propelled Bomb | Slow-Down Shoes | Snowboard | Sphere | Spikes | Spring | Spinning Top | Star Post ( Star Circle) | Super Emerald | Switch | Transport | Zip Line
Angel Island | Barrel | Blue Knuckles | Conveyor Belt | Corkscrew loop | Crusher | Debug Mode | Fireball Cannon | Flipper | Flywheel | Freezing Machine | Giant spear | Goal | Gravity Control Switch | Gumball | High-speed elevator | Icicle | Jewel Radar | Perfect Bonus | Platform-raising Wheel | Pole Elevator | Relief | Reverse | Ring Shooter | Seesaw | Shuttle loop | Slot Machine | Sonic & Knuckles • Sonic the Hedgehog 3 | Spiked ball | Strange Relief | Tunnelbot | Warp Point | Winding Tunnel | Wonderman