Uplifted by the Nr~klat who were extremely hard on the proto-Karrank% during clienthood, making profound force-gene transformations and pushing the young race very fast.

From a simple race of subterranean burrowers, digging tunnels and foraging under the roots of giant trees, they were turned into giant excavators, seeking riches for their masters. The resulting pressures pushed the poor Karrank% past a breaking point.

As emerging psi-adepts, they waited till a grand conclave of the Nr~klat, then mentally blasted their patrons back to a pre-sapient state.

The Uplift Institute thereupon resettled the Karrank% to the planet Kithrup. The 7 metre tall Karrank% generally rest catatonically still, in vertical shafts, with the metal-tainted ocean damping their psi-forces.

Sources: Contacting Aliens, An Illustrated Guide to David Brin's Uplift Universe, Startide Rising