Ironically this came from an auction which had a lot of german items including some pottery. Here is some interesting info. I'm pretty sure this is a mixing/kitchen bowl. I dont what else it would be used for.
The unique characteristics of salt glazing were discovered in the Rhineland of Germany, probably in the 14th century. Initially, the process was used on low fire earthenware. By the 15th century, small pottery towns of the Westerwald, including Höhr-Grenzhausen, Siegberg, Köln, and Raeren in Flanders, were producing a salt-glazed stoneware. (Nelson, p. 33-34) Westerwald Pottery was characterized by stamped medallions and the use of a cobalt oxide based colorant for decoration. Salt kilns were used extensively in western Europe in the 16th and 17th centuries, particularly in Germany, Scandinavia and the British Isles.
[edit] American salted stoneware
Salt ware was also popular during the colonial period in North America and in the early years of the United States. Initially, significant amounts of salt ware was imported from England. Americans began producing salt-glazed stoneware circa 1720 in Philadelphia, Pennsylvania, and Yorktown, Virginia, and American Stoneware became the predominant houseware of nineteenth century America. Contemporary potters in both North and South Carolina are well known for ongoing salt fired production. These independent craftsmen, generally operating small family oriented businesses in rural areas, produce ware in both traditional and personalized forms. Traditionally, each business in this area has been known for their distinctive output and decorative motifs.