Crast
this small crustacoid creature was native to the planet Pria, and served as one of the primary food sources fro the Priapulin. The crast and the Priapulin have a unique relationship, in that the digestion of a crast triggers reproduction in the crast. Although the digestion eventually kills the crast, the eggs of the crast are actually nurtured within the Priapulin's digestive juices. Once the young crasti reached maturity, they were regurgitated by the Priapulin to live out their lives. In another strange twist, the Priapulin have evolved to only consume those crast which bear eggs.