Liquid mammalian secretion that is digested as a solid by consuming infants.

Milk is produced, uniquely, by members of Class Mammalia. It is as a nutritious body secretion is a liquid food that, as it is digested in the stomach, takes the form of a semi-solid food.

As a consequence, the baby is not hit with a bolus of nutrients but instead digests its food much more slowly than would be the case were it purely liquid.