Barley is the most commonly malted grain, in part because of its high content of enzymes, though wheat, rye, oats, rice, and corn are also used. Also very important is the retention of the grain's husk, even after threshing, unlike the bare seeds of threshed wheat or rye. This protects the growing acrospire (developing plant embryo) from damage during malting, which can easily lead to mold growth; it also allows the mash of converted grain to create a filter bed during lautering (see brewing).