Existing shapes can also be converted into tables by inserting some rows and columns into them from the Table tab. As with a new standalone table, you select the number of rows and columns and then click on Insert Table. This inserts the desired table into the shape or shapes currently selected. Any text inside the shapes is placed in the first cell of the table.
Non-rectangular shapes may also contain tables:
Depending on how many rows or columns you selected, your shape may grow to accommodate the inserted table.