Fresh water is turned into an iceberg by the splitting or calving of glaciers. Bergs also vary wildly in shape and can be steep or irregular with rounded or flat tops. Because wind and water erode them, they constantly shift shape.
An iceberg about the size of an automobile is called a growler, but sizes can be much bigger. The tallest iceberg ever found was in the North Atlantic and approximately as tall as a 55-story building. It reached 550 feet above sea level, but the bulk of it was beneath the water, which is typical.