A stamping die taken from the wreckage of a defeated Knuckle Duckle — think of it as a keepsake from Aino.
A philosopher from Sumeru once argued that self-replication is a unique characteristic of life, an unparalleled achievement that no man-made object can mimic. The power to reproduce is the key that separates mankind from the divine.
However, if a machine is given an exact mold that it can use to replicate itself, mold included, then can not this too be considered perpetual self-replication? The former master of the silent, blue-haired maid who stands by Aino's side once pondered that same question but ultimately dismissed it out of fear that a perpetually self-replicating machine would consume everything on the planet's surface.
Such problems have never concerned Aino. This machine will not exhaust the world's resources to multiply itself just yet — after all, it's just a duck.