this is 'tonic', by reinhard dienes, a piece of furniture that can be either a standup bookcase or a low storage unit, by flipping the oak shell and moving the feet.
i thought the legs were maybe black rubber, but seeing the closeup shot (below) it looks like they are darker stained wood. i really like the contrast.
about the design, dienes says:
This transformation allows Tonic to adapt itself to changing living situations and desires.
im not sure how often the user might do this in reality, but it's still a nice idea.