A heavy sediment consisting of dead yeast cells and other solid matter such as grape pulp, pips and so on. Keeping the wine on the lees, especially if they are stirred from time to time, may be beneficial to the wine. It imparts extra flavour and body to the wine. Eventually, however, they must be removed. This may be achieved by racking the wine off the lees. Residual solid matter may be removed by filtration.