This part is turned by the auger motor. Pellets will drop down from the hopper onto this part. When being turned by the auger motor it will push the pellets through the feed tube and deposit them into the firepot.
Overtime this part will wear down or warp from constant exposure to the heat from the firepot. Or, if something gets jammed in the feed tube during normal operation it can also damage the auger.
In the manual for the Oklahoma Joe’s Rider DLX Pellet Grill 900 and 1200 models this is listed in the parts key as item #9