Unwanted dialog box for sorting appears at top of every column

When I opened a spreadsheet today, a small icon that opens to a dialog box for sorting appears at the top of every column. This effect also occurs if I open the SS with OO Calc.

I must have hit some key combination that caused this effect, but I don’t want it. How do I get rid of it? Thanks for your help.

I found the cause of my problem. It’s the Auto Filter control (looks like a funnel) to the right of the other sort control icons in the toolbar.