Tunlets are very small for an invertipet and can easily fit on a quarter. They're known for being extremely hardy animals, and they can survive in nearly any environment! However, they thrive best in aquatic or humid conditions as they need moisture to breathe. If they're left in an unsuitable environment for an extended period of time, tunlets will go into a dormant state. While dormant, they will curl into a ball, surround themselves with a small protective bubble, and will not respond to external stimuli until the conditions are more suitable. Some tunlets have even been known to survive exposure to outer space in this dormant state! (Don't try that at home.)

Due to their hardiness, tunlets are often kept as pets, and they are especially common in biology classrooms. They're omnivorous and will feed on nearly anything, but they vastly prefer living food (algae, plants, or small invertebrates) to any sort of pellet or detritus.