I downloaded a workbook that had hidden columns so I copied the worksheet to
a blank worksheet because I didn't know the password that protects it. Then
a multi-row triangle appeared across two columns.

What does this triangle mean? Why does it move? Why does it disappear?

The triangle is always one of the hidden columns and the adjacent unhidden
column to the right. The first row is always the first row with numbers and
the last row is always the bottom row with numbers. The top three rows
contain text.

I am using Excel 2007. Original workbook was probably in Excel 2003 format.

And is it normal to be able to circumvent worksheet protection by simple
copying? I haven't used Excel extensively in probably 15 years and this
seems strange.

Just curious.

Thanks.

David