A Shiro's main defense was its spiny shell, which it would withdraw into.
Shiros rolled in mud and collected dirt and seeds between their shell ridges. Tooke-trap plants grew and flourished in those soil pockets, creating the symbiotic "Shiro-trap". The Tooke-plants also provided camouflage for Shiros from predators, especially from the Saw-toothed grank which was the Shiro's main predator due to its ability to break through tough shells.
Shiros also provided locomotion for the Tooke-traps.