- "The mother ship. It was a gigantic, three-legged insect. The center was a single, bloated sphere. The sphere was flatter on the bottom, and from the bottom hung a weird, mismatched series of tendrils. Like the tendrils of a jellyfish. Each one must have been a quarter-mile long. Around the sphere were three legs, bent up, then back down, exactly like a spider's legs."
The Yeerk Pool Ship also known as the Yeerk mother ship contains a large Yeerk Pool as well as its own Kandrona source (which can only emit Kandrona rays to the pool onboard the ship). It is gigantic in size and resembles a black spider, with a fat spherical body and a flattened bottom, three leg-like engines, and several small tendrils on the bottom that act as sensors. The side of the ship has a docking port, which is an opening where smaller ships enter the body of the ship, that is so large Bug Fighters are dwarfed by it. The Pool Ship orbits high above Earth, cloaked from detection by human radar.
- "The Pool ship looked like a fat, swollen, three- legged spider. I'd seen it before, up in orbit, high above planet Earth. The Pool ship: home of the Yeerk invasion force, base of the Bug fighters. It was a space-going Yeerk pool, well-defended, dangerous, but essentially a portable barracks, a giant mess hall that served up hearty doses of Kandrona rays, the sustenance that a Yeerk must have every three days or die. The Bug fighters rose to greet their mother, swarming around the Pool ship, bristling, daring anyone to attack."
The Animorphs first encounter the Pool Ship when they are captured by Visser Three, who takes them in his Blade Ship through the Pool Ship's docking port, and inside the Pool Ship, where they are held captive in a holding cell. They Animorphs only escape because one of Visser One's Hork-Bajir Controller troops give them instructions to find an escape pod, in order to embarrass Visser Three.
When the Animorphs destroy the Earth-based Kandrona, the Yeerks are temporarily weakened because they must rely on the pool ship Kandrona for three weeks, until a replacement Kandrona arrives. 
Near the end of the war, after the Animorphs had destroyed the Yeerk pool, Visser Three, who had recently been promoted to the rank of Visser One), temporarily transferred his headquarters onto the Pool ship and ordered it to land on Earth. The visser also ordered the complete obliteration of the Animorphs' hometown in order to create a sort of dead zone around the ship. The ship was to provide nourishment for ground-based Yeerks until a new pool could be created. The Animorphs captured the Pool ship and Visser One, with the help of the military, the Auxiliary Animorphs, Toby's Hork-Bajir, a group of Taxxons led by Arbron, and a split faction of Yeerks led by Tom who wanted to create their own Empire.
|Andalite technology||Dome Ship | Escafil Device | Hirac delest | Mirrorwave call | Z-space transponder | Morphing | Mag-Hover Truck | Quantum Virus | Shredder | Gleet Bio-Filter|
|Yeerk Technology||Anti-morphing ray | Dracon beam | Gleet Bio-Filter | Kandrona | Kandrona Rays | Nova-class Empire Ship | Pool ship | Blade ship | Mag-Lev Train | Hunter-Killer Robot | Yeerk Pool | Bug fighter|
|Ketran Technology||Explorer | Time Matrix | Fire-And-Forget Explosive Homer | Uninet | Adge|
|Other||Dropshaft | Ixcila (Arn) | Pemalite crystal | Skrit Na Saucer | Hawjabran Colony Ship | Hawjabran Freighter|