BIO: The mature Congle is enthralled with the idea of using one object in diverse ways, hence the continued use of its eggshell drum. Another example: hidden by its drum most of the time, a Congle's tummy is inconceivably soft. It makes a great pillow for when other Monsters need a quick nap, and it's always more than happy to oblige. When the drum invariably wears out from so much use, it gets upcycled into a snazzy ottoman or decorative planter.
