Some spell checkers don't recognize "mutable" as a word, but the Oxford English Dictionary has this citation from 1646:
There is no East and West in Nature; nor are those absolute and invariable, but respective and mutable points.
Thomas Browne · Pseudodoxia epidemica · 1st edition, 1646 (1 vol.). London: printed by T. H. for Edward Dod
Somehow that seems appropriate. Foldit has a few mutable points.