Mash rake

The mashing fork is used to mix the mash by hand to ensure the various grains are properly homogenized and wet everywhere, so no starches are wasted.

In modern parlance, the term 'rake' is used most commonly to refer to mechanical knives used to cut the mash bed to optimize the efficiency of the runoff and 'fork' is most commonly used to refer to the traditional, mostly archaic, tool.

Before the industrial age, the mash fork was an instrument made of wood with a long handle, somewhat resembling an oar with large holes in the blade.

Large modern brewers, however, use mechanical apparatus to mix the mash instead of manual labour.

[1] Media related to Mash rakes at Wikimedia Commons

A closeup of the head of a traditional wooden mashing fork.
St. Arnold of Soissons , the patron saint of Belgian brewers, is often depicted with a mash rake.