Several months ago, we noticed that one of our Middle Kingdom statuettes was spinning around imperceptibly slowly in its new case in our Egyptian Worlds gallery. We set up a time lapse camera to take one image every minute for a week. This is the result.
The cause may be subtle vibrations from footfall or traffic outside, but the statuette has been on a glass shelf in about the same place in the gallery for decades and has never moved before -- and none of the other objects in the case move in any way.
A mystery? See for yourself.