"This is an underground monster Terragaia. This monster sneaks into silicon, reassembles the system and to create the terror liquid. From its horns emit a destructive beam, and spews out chlorine gas."
- ―Takeshi Todo
Subtitle: Subterranean Monster (地底怪獣 Chitei Kaijū)
Gridman the Hyper Agent
Angered by the foul taste of the water dispenser at his town's park, Takeshi Todo had Terragaia go into a city water plant to turn the water supply into hydrochloric acid. With its gas, Terragaia could melt circuit panels and burrow underground in the computer world. While Yuka Inoue was analyzing a sample of the tainted water, Gridman alerted the gang about Terragaia. However, Gridman walked into a trap when he entered the plant's computers. His ankles were shackled and was being asphyxiated by Terragaia's gas. Luckily, Ippei had finished designing Thunder Jet and Twin Driller; using the new mecha, Twin Driller broke the shackles and Thunder Jet used the Thunder Ring to muzzle Terragaia. Unable to spray its gas, Terragaia was destroyed by Gridman's Grid Beam.
- Terragaia's body design was later used for the inspiriation for Dazzlba and later Skubone.
- Terragaia might be a tribute to the monster Antlar.
- Terragaia shares his title with Telesdon.
- Height: 89 m
- Weight: 62,000 t
- Origin: Cyberspace
- Powers and Weapons
- Electric Beam: Terragaia can fire a beam of electricity from its horns.
- Chlorine Gas: From its mouth, Terragaia can fire a cloud of chlorine gas.