List of impossible objects

1. Blivet (a.k.a. Poiuyt or Impossible Fork)

2. Penrose Triangle

3. Impossible cube

4. Penrose Staircase

5. Möbius band

6. Klein bottle (this object is possible to make, so it shouldn't be on this list, but it is, according to Wikipedia, "a two-dimensional manifold against which a system for determining a normal vector cannot be consistently defined.", unlike a normal bottle)

7. Möbius snail