Lentils are legumes of typically biconvex shape. In English they are called "lentils", while the Latin name is "lens". This etymological root lies precisely in the fact that thanks to their shape they are very similar to an optical lens.
In the Jewish tradition of mourning, lentils accompanied by hard-boiled eggs represent a traditional food, as their circular shape symbolizes a person's life cycle (from birth to death).
Lentils were the progenitor of the diet of the ancient Iranians, who ate them daily in the form of a stew with rice.
Today they are commonly used in Ethiopia, where a very similar recipe is prepared called "kik" or "kik wot"; this represents one of the most consumed national dishes, especially as an accompaniment to the so-called "injera" bread. Still in Ethiopia, yellow lentils are cooked in the form of non-spicy stew to be used as the first solid food in weaning.
In the Indian subcontinent, the "dhal" (or "lentil curry") is eaten daily along with rice and "roti" (unleavened bread). Here, boiled and canned lentils are commonly used as the main ingredient of many vegetarian curries and as a filling for "Dal Parathas & Puris". They are also used in many regional desserts and are considered among the best foods of the Asian diet, as they preserve their nutritional characteristics more than the other legumes.
In Italy and Hungary, eating lentils at New Year symbolizes the hope of prosperity for the coming year, probably due to their circular shape similar to a coin.
