A drupelet is one of the small, single-seeded fruit segments that cluster together to form an aggregate fruit such as a raspberry or blackberry, as opposed to a single drupe like a peach, which is one fruit built around one pit.
Each drupelet is roughly 5-10mm, rounded, and contains one small seed; dozens to hundreds cling together around a central core, or receptacle, to form the berry. When ripe, raspberry drupelets separate cleanly from the receptacle, leaving the berry hollow, while blackberry drupelets stay attached to it - the reason raspberries are hollow and blackberries are not.
Drupelets are used in desserts, jams, and other sweet preparations for their bright, tangy flavor and juicy texture, and occasionally in savory sauces and marinades. They are highly perishable and should be handled gently and used soon after harvest; they can be frozen, though freezing softens their texture.