The Medusans are a sapient species of telepathic non-humanoids which are described as having the most beautiful thoughts known in the galaxy. Their physical appearance in sharp contrast is so hideous that even the quickest glance at them will cause madness and might even result in death by multiple organ failure in a Human observer. Vulcans are more resistant to the effects, being able to stare at a Medusan while wearing a special kind of visor. The Medusans are also regarded as excellent outer space navigators, partially a result of their natural sensory system being radically different from that of other races.