Erratic

[Sarah]

Any stone or material that has been borne away from itsoriginal site by natural agencies; esp., a large block or fragment ofrock; a bowlder.

[Sarah]

[shambolic]; [disorganized]; [unpredictable].

[Julene]

Not even or regular in pattern or movement; unpredictable.

[exinilu]

moving or behaving in a way that is not regular, certain, or expected: