In the station, they meet Halrloprillalar Hotrufan ("Prill"), a former crew member of a spaceship used for trade between the Ringworld and other inhabited worlds. When her ship returned to the Ringworld the last time, they found that civilization had collapsed. The crew managed to enter the Ringworld, but some of them were killed and others suffered brain damage when the device that let them pass through the Ringworld floor failed. From her account, Louis surmises that a mold was brought back from one of the other planets by a spaceship like Prill's; it broke down the superconductors vital to the Ringworld civilization, dooming it.