This is a lovely early 1800s coquilla nutmeg grater in the unusual shape of a pear. The nutmeg grater unscrews in the middle to reveal a grater which unscrews for  storage of nutmegs. These were pocket nutmeg graters used to grate fresh nutmeg into mulled wine etc.

It measures 

Antique Nutmeg Grater - in the shape of a pear