Ytram is a type of tiny frog native in Riven. It belongs to the subterranean ecosystem of that Age. They are harvested by the Rivenese for the chemicals of their bodies.
The Moiety extracted poison for their darts; Gehn also used them to make extracts for his pipe and had made traps to catch ytrams. One such trap is found in a cave on the Book Assembly Island. His office in that island had a series of jars with conserved ytram bodies.
Gehn feared that the shifting of the plates would harm the subterrannean ecosystems, however it seems that ytrams flourished. On his last year on Riven he had a rich harvest and refined a particularly pleasant extract for his pipe.
A cave opening on Jungle Island formed the silhoutte of an ytram; the Moiety had designated to it the number 3.