they inhabit a vast ocean world and unless they're captive, only briefly glimpse what's aboe the surface. the world above sea level is basically outer space to them.
occasionally they will see strange objects floating on the water (boats and ships). these objects don't look natural and make strange noises. they also sometimes seem to want to abduct their brothers and sisters and often do, sometimes never to be seen again.
once in a while a human might dive down there and encounter a whale or something. these encounters are brief, mysterious and lack communication. they are, from the whale/dolphin perspective, essentially alien visits from an unknown world above.
discus.
