A sheep is a passive animal that may be seen on the island in the center of the Lake frolicking or being chased by the wolf.
Sheep, along with flying sheep (Lentolammas) and buzzing sheep (Suhiseva lammas), are the three possible results of drinking or being stained with a polymorphine, and one of many more from chaotic polymorphine. You cannot attack when transformed into a sheep. However transforming into one of the flight-capable sheep is very useful to reach certain areas, or escape from a Holy Mountain without angering the gods.
A rock spell with homing will try to hit a sheep, but cannot damage it.