C1ExcelBook can load and save all types of shapes present in Excel sheets.
However, only image shapes are fully exposed (as XLPictureShape objects).
All other object types are loaded and saved as XLOpaqueShape objects that cannot be modified. These include graphical elements (such as lines, rectangles, and arcs), VBA controls (such as edit boxes, and buttons), and comments.
System.Object
C1.Excel.XLShape
C1.Excel.XLOpaqueShape