Obturaculum Somniorum

Obturaculum Somniorum is a device created by Bernie to contact the Dream Dimension, it opened a door through which the Dream Beavers could enter our world and the only way to prevent this would be keeping the Obturaculum working forever.

Bernie kept the Obturaculum hiden inside an old book for 40 years, but Casey broke it to save the turtles' lifes, releasing the Beavers in our dimension.