Find Unassociated Shape(s) on a Sheet

I want to check and/or set the Properties for unassociated Shapes on multiple Sheets.
In VBA and C# the Sheet has no Child-Shapes. Finding them is therefore not possible.
By selecting the Shapes I can get to them (ActiveSheet.Selection): They say the Sheet is their Parent ! ??

Is there a way to find/collect all the (unassociated) Shapes on a Sheet? Or to select all ( Ctrl><a> ) on the Sheet?
In what I have found for "SheetOperations" I need to give the Shape-ID to find it, or they have to be selected.