Thaumatrope; what a deceptively simple name for such a simple little toy.  Say it with me “thaw -ma-trope.”  These toys are super simple two sided precursors to modern animation.  A thaumatrope has a different image on each side.  When spun rapidly the two images give the impression of blending into one.  It’s kind of like ice age animation.  It’s simple but also a little magic.