A crock is a pottery container sometimes used for food and water, synonymous with the word pot, and sometimes used for chemicals.
Crocks are made from stoneware, which is a nonporous ceramic that is water-tight, even without glaze.
The meat is kept submerged in the brine by two semicircle weights designed to fit inside the crock.
Smaller crocks (1-10 gallons) are commonly used for preserving vegetables such as cucumbers for pickles, and cabbage for sauerkraut.
Preserving food in this manner allows people to keep summer vegetables throughout the winter months when gardens and crops are not producing.