a moulded short 'rod' shaped item.  It's a stirrer which is used in the making of individual mixed cocktails,  especially an 'Old Fashioned'.  The base end of the muddler (ground and acid-etched end) is used to crushed sugar cubes soaked with Angostura Bitters (or similar) and then to blend remaining ingredients.

A wooden mallet used to smash fruit.

a thick rod used to crush and mix fruit and sugar in drinks. Also, used to free the bubbles in champagne.