Although this article is based on official information, the actual name of the article's subject is pure conjecture.
This article's name is conjectural.
Tunnelbot is a robot built by  Dr. Robotnik, that appears at Lava Reef Zone in and Sonic & Knuckles . The robot serves as an minor obstacle during the gameplay, as it seems to be a larger variation of the first Sonic Mania Tunnelbot seen in Marble Garden Zone with four drill attachments.
Sonic & Knuckles
Knuckles encountering the Tunnelbot in Lava Reef Zone Act 1.
and its add-on game Sonic & Knuckles , the Tunnelbot appears three times in Sonic the Hedgehog 3 & Knuckles Lava Reef Zone Act 1, 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. The player can hit it with a Spin Attack an arbitrary number of times but cannot be defeated this way.
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.
, Tunnelbots appear again in Sonic Mania Lava Reef Zone Act 1. Once again, the player can land numerous hits on it, but the Tunnelbot cannot be defeated by regular means.
In gameplay, the player faces off with the Tunnelbot in the iron fence area. Once again by drilling at one place, the drone causes the floor to crumble, while falling down to the lava pool. Midway through Act 1, one Tunnelbot is seen causing the lava pool to raise, as the player has to escape it, while the Tunnelbot once again falls down to the pit.
The boss of Lava Reef Zone Act 1,
Drillerdroid, is an advanced model of the regular Tunnelbot with a heavily-armed head drone and bulkier parts around its drill attachments.
If the player manages to pass through the Tunnelbot safely, the player can usually find an item or something else from the other side. In , an Sonic & Knuckles extra life ( Sonic) or alternative pathway ( Knuckles) can be found.
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