According to Google translate the name translates to "Doom Turtle"
(and yes, it does look like a famously unproduced American superheavy assault gun)
It's honestly ridiculous and of limited practical value on almost every battlefield, but I still kinda dig it.
(record sheets includes the base model and the obvious artillery and artillery cannon versions)
Untergangsschildkröte Assault Gun
Mass: 95 tons
Movement Type: Tracked
Power Plant: 285 Light
Cruising Speed: 32.4 kph
Maximum Speed: 54 kph
Armor: Heavy Ferro-Fibrous
Armament:
1 Improved Heavy Gauss Rifle
Manufacturer: Unknown
Primary Factory: Unknown
Communication System: Unknown
Targeting & Tracking System: Unknown
Introduction Year: 3125
Tech Rating/Availability: E/X-X-F-E
Cost: 16,272,750 C-bills
Type: Untergangsschildkröte
Technology Base: Inner Sphere (Advanced)
Movement Type: Tracked
Tonnage: 95
Battle Value: 2,005
Equipment Mass
Internal Structure 9.5
Engine 285 Light 19
Cruising MP: 3
Flank MP: 5
Heat Sinks: 10 0
Control Equipment: 5.0
Power Amplifier: 0.0
Armor Factor (Heavy Ferro) 372 19
Internal Armor
Structure Value
Front 10 120
R/L Side 10/10 91/91
Rear 10 70
Weapons
and Ammo Location Tonnage
Improved Heavy Gauss Rifle Front 20.0
Improved Heavy Gauss Rifle Ammo (32) Body 8.0
Armored Motive System Body 14.5