This prune-powered device was originally intended to make cheese very quickly; it can age anything almost instantly. (When low on prunes, it has been known to fire a hail of prune pips).
However, when powered by plums, it has a reversal effect, un-aging any aged person or substance. It is unknown whether it only unages aging that it caused, or whether it can be used for eternal youth.
Seen in Rest Home Rangers.