About that crystal ball

[Villavic]

I don't remember if this was asked before.

The crystal ball (from Rumours, The Dance,) appeared at first in the 1975 white album cover. Is there a story about that ball? Why they included it? I don't remember any comment in Mick's book. Actually I don't know how or why they did that cover. Mick said they used the ball again in Rumours, like following the good luck from the previous album, but don't know why they used it before.