If you were to say "nigella" to most foodies, they'd probably think of British celebrity chef Nigella Lawson rather than the spice. Nigella seeds - which come from the Nigella sativa plant and go by other names, including black cumin, kalonji and kalo jira - look like small, sharp, jet-black sesame seeds. They don't have much aroma until they're cooked, either by toasting in a dry skillet, baking or lightly frying in oil, which is then imbued with their flavour. They have a crumbly texture and taste similar to dried oregano.
Nigella is said to aid digestion, ease respiratory problems, calm the nerves and strengthen the immune system.
In the kitchen, nigella is sometimes included in the complex spice mixture known as ras el hanout. In Indian cuisines, they're sprinkled over breads before they're baked, and added to curries and dals.