The Grensuhlians are a race of deep-water isolationists who are about as non-humanoid as is possible. The Grensuhlian 'individuals' are referred to as 'clusters' because each cluster is really made up of much smaller, simpler creatures that range from dozens to hundreds based on age. These more basic creatures spawn asexually over time using some kind of coordinated multi-cellular division, and the older the Grensuhlian, the more of them will compose the larger individual's body. However, in the case of serious illness or starvation, the Grensuhlian cluster may actually shrink, as the creatures that make it up consume each other to stay alive.
The Grensuhlians are powerful telepaths. They do not hear sound, though they can detect atmospheric vibrations in a cruder way, much like Humans might feel deep, bass-y sounds. The more clusters that make up a Grensuhlian, the stronger its telepathic ability and the greater its intelligence - which is often profound.
The ancients among the Grensuhlians are renowned for their capability in performing the most complex mathematics known to the Younger Races. It is, however, very difficult to secure their help.
The Grensuhlians virtually never permit aliens to visit their homeworld of Odysseus, primarily because they are extraordinarily sensitive to foreign biological or chemical contamination. The deep seas maintain a very constant environment and the Grensuhlians do not deal with inconstancy well.
Further, if one of their species leave the planet, as a few have, they are never permitted to return home. Nobody's ever made money on off-planet destination resorts for Grensuhlians!
Beyond this, very little is known about this enigmatic race.