Nympus

The Nympus are the native sapient inhabitants of Ganymede.

Biology
They've been described as grotesque beings with short knee-less legs (jointed only at the hip and ankle), long arms webbed to their bodies by a membrane, and noseless faces which are almost hidden by the mushroom-like shape of the top of their heads.

Culture and society
They build up floating houses which can be carried over long distances during the flood seasons.

Appearances

 * "Tidal Moon", by Stanley G. Weinbaum and Helen Weinbaum (1938)