The tarr are formed when a largo eats a plort unlike the ones it produces. A terrible transformation occurs that turns the slime into a sludge filled with a swirling, prismatic array of colors and a relentless appetite. The tarr seek only to consume and replicate. Because of this, it can spread rapidly throughout the ranch. The only way to stop a tarr outside of incinerating it or throwing it into the slime sea is with fresh water. One splash will stop a Tarr from spawning new Tarr, and repeated splashes will destroy it entirely. Alternatively many ranchers recommend running away with their arms waving, and screaming.
The tarr are the single biggest threat to ranchers. The tarr will seek out slimes to consume and replicate themselves, but will also devour chickens, rot crops in their proximity, and even devour ranchers! Remember: ranching largos may be highly profitable, but one stray plort and you could wind up with a devastating tarr outbreak.
The Tarr produce no plorts, only more tarr. And then more tarr still