Black cumin seeds, also known as Nigella sativa, are tiny, black, crescent-shaped seeds with a slightly peppery and bitter flavor. They are often referred to as "kalonji" in some cultures, particularly in South Asia. These seeds are commonly used as a spice in cooking, especially in Middle Eastern, Indian, and Mediterranean cuisines. They are often added to breads, curries, soups, and salads for an aromatic kick.