That's because they're the classic places for 'something' to appear. Like the grand piano that plays by itself, the human anatomical model that moves by itself ...
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何か， なにか， なんか
1. something, some, any
2. somehow, for some reason
3. (so) what (are you trying to say)?, what (do you mean)?
1. to leave, to exit, to go out, to come out, to get out
2. to leave (on a journey), to depart, to start out, to set out
3. to move forward
4. to come to, to get to, to lead to, to reach
5. to appear, to come out, to emerge, to surface, to come forth...
1. to do, to carry out, to perform
2. to cause to become, to make (into), to turn (into)
3. to serve as, to act as, to work as
4. to wear (clothes, a facial expression, etc.)
5. to judge as being, to view as being, to think of as, to treat as, to use...