If there happens to be a heavy snowfall on a beach, the action of wind and waves can produce balls of ice with snow in the center. This happens when the water temperature is near freezing. Nova Scotia fishermen call these ice-balls “lollies.” The process is similar to rounding of pebbles on the beach, but much faster.
Snow rolls result when the wind catches snow on sloping ground under the right conditions of temperature, humidity, and wind speed. Rolls can also be formed due to gravity if there is some disturbance such as snow falling off a tree.
You can download a Powerpoint presentation about these phenomena here. (The file has been checked for viruses.)