Shapes assigned to no layer...and no background

[NaomiApricot]

I've inherited a Visio diagram that has several tabs.  I want to clean it up and re-assign layers, and have discovered that on one of the tabs, nearly all the shapes are not assigned to any of the 7 layers that were created originally.  The way I judge this is going into layer properties and unchecking all of the "visible" boxes.  Nearly every shape remains visible.  Where are they, if not assigned to a layer?   

thanks!

[Paul Herber]

Hi Naomi, in Visio shapes don't have to be on a layer. Technically, shapes belong to pages, not layers. A page can have one or more layers and a shape can belong to one or more layers.

[NaomiApricot]

Thanks Paul!  This answers the question.