Carom seeds are the seeds of the ajwain herb, or Trachyspermum ammi. They’re common in Indian cuisine.
Although referred to as “seeds,” carom seeds are the fruit of the ajwain herb.
They’re slightly green to brown in color and have a pungent, bitter taste. They look similar to cumin seeds, but their taste and aroma are closer to that of thyme.
They’re often sold as whole seeds but can also be ground into a powder and used as a cooking spice.